diff --git a/CHANGES.rst b/CHANGES.rst
index 5767ec7792..ba6929c435 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -1,3 +1,12 @@
+Synapse 0.32.2 (2018-07-07)
+===========================
+
+Bugfixes
+--------
+
+- Amend the Python dependencies to depend on attrs from PyPI, not attr (`#3492 <https://github.com/matrix-org/synapse/issues/3492>`_)
+
+
 Synapse 0.32.1 (2018-07-06)
 ===========================
 
diff --git a/changelog.d/.gitignore b/changelog.d/.gitignore
new file mode 100644
index 0000000000..f935021a8f
--- /dev/null
+++ b/changelog.d/.gitignore
@@ -0,0 +1 @@
+!.gitignore
diff --git a/changelog.d/3463.misc b/changelog.d/3463.misc
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/changelog.d/3464.misc b/changelog.d/3464.misc
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/changelog.d/3496.feature b/changelog.d/3496.feature
new file mode 100644
index 0000000000..6a06a7e755
--- /dev/null
+++ b/changelog.d/3496.feature
@@ -0,0 +1 @@
+Include CPU time from database threads in request/block metrics.
diff --git a/changelog.d/3497.feature b/changelog.d/3497.feature
new file mode 100644
index 0000000000..4e333155b6
--- /dev/null
+++ b/changelog.d/3497.feature
@@ -0,0 +1 @@
+Add CPU metrics for _fetch_event_list
diff --git a/changelog.d/3501.misc b/changelog.d/3501.misc
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/setup.cfg b/setup.cfg
index fa6f2d1ce4..9b5b75cd60 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -19,3 +19,15 @@ max-line-length = 90
 #  W503 requires that binary operators be at the end, not start, of lines. Erik doesn't like it.
 #  E203 is contrary to PEP8.
 ignore = W503,E203
+
+[isort]
+line_length = 89
+not_skip = __init__.py
+sections=FUTURE,STDLIB,COMPAT,THIRDPARTY,TWISTED,FIRSTPARTY,TESTS,LOCALFOLDER
+default_section=THIRDPARTY
+known_first_party = synapse
+known_tests=tests
+known_compat = mock,six
+known_twisted=twisted,OpenSSL
+multi_line_output=3
+include_trailing_comma=true
diff --git a/synapse/__init__.py b/synapse/__init__.py
index 81a6e06199..3cde33c0d7 100644
--- a/synapse/__init__.py
+++ b/synapse/__init__.py
@@ -17,4 +17,4 @@
 """ This is a reference implementation of a Matrix home server.
 """
 
-__version__ = "0.32.1"
+__version__ = "0.32.2"
diff --git a/synapse/api/auth.py b/synapse/api/auth.py
index 088b4e8b6d..6dec862fec 100644
--- a/synapse/api/auth.py
+++ b/synapse/api/auth.py
@@ -18,15 +18,16 @@ import logging
 from six import itervalues
 
 import pymacaroons
-from twisted.internet import defer
 from netaddr import IPAddress
 
+from twisted.internet import defer
+
 import synapse.types
 from synapse import event_auth
-from synapse.api.constants import EventTypes, Membership, JoinRules
+from synapse.api.constants import EventTypes, JoinRules, Membership
 from synapse.api.errors import AuthError, Codes
 from synapse.types import UserID
-from synapse.util.caches import register_cache, CACHE_SIZE_FACTOR
+from synapse.util.caches import CACHE_SIZE_FACTOR, register_cache
 from synapse.util.caches.lrucache import LruCache
 from synapse.util.metrics import Measure
 
diff --git a/synapse/api/errors.py b/synapse/api/errors.py
index 227a0713b2..6074df292f 100644
--- a/synapse/api/errors.py
+++ b/synapse/api/errors.py
@@ -17,11 +17,11 @@
 
 import logging
 
-from canonicaljson import json
-
 from six import iteritems
 from six.moves import http_client
 
+from canonicaljson import json
+
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/api/filtering.py b/synapse/api/filtering.py
index aae25e7a47..25346baa87 100644
--- a/synapse/api/filtering.py
+++ b/synapse/api/filtering.py
@@ -12,15 +12,15 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-from synapse.api.errors import SynapseError
-from synapse.storage.presence import UserPresenceState
-from synapse.types import UserID, RoomID
+import jsonschema
+from canonicaljson import json
+from jsonschema import FormatChecker
+
 from twisted.internet import defer
 
-from canonicaljson import json
-
-import jsonschema
-from jsonschema import FormatChecker
+from synapse.api.errors import SynapseError
+from synapse.storage.presence import UserPresenceState
+from synapse.types import RoomID, UserID
 
 FILTER_SCHEMA = {
     "additionalProperties": False,
diff --git a/synapse/api/urls.py b/synapse/api/urls.py
index bb46b5da8a..71347912f1 100644
--- a/synapse/api/urls.py
+++ b/synapse/api/urls.py
@@ -15,8 +15,8 @@
 # limitations under the License.
 
 """Contains the URL paths to prefix various aspects of the server with. """
-from hashlib import sha256
 import hmac
+from hashlib import sha256
 
 from six.moves.urllib.parse import urlencode
 
diff --git a/synapse/app/__init__.py b/synapse/app/__init__.py
index 9c2b627590..3b6b9368b8 100644
--- a/synapse/app/__init__.py
+++ b/synapse/app/__init__.py
@@ -14,9 +14,11 @@
 # limitations under the License.
 
 import sys
+
+from synapse import python_dependencies  # noqa: E402
+
 sys.dont_write_bytecode = True
 
-from synapse import python_dependencies   # noqa: E402
 
 try:
     python_dependencies.check_requirements()
diff --git a/synapse/app/_base.py b/synapse/app/_base.py
index a6925ab139..391bd14c5c 100644
--- a/synapse/app/_base.py
+++ b/synapse/app/_base.py
@@ -17,15 +17,18 @@ import gc
 import logging
 import sys
 
+from daemonize import Daemonize
+
+from twisted.internet import error, reactor
+
+from synapse.util import PreserveLoggingContext
+from synapse.util.rlimit import change_resource_limit
+
 try:
     import affinity
 except Exception:
     affinity = None
 
-from daemonize import Daemonize
-from synapse.util import PreserveLoggingContext
-from synapse.util.rlimit import change_resource_limit
-from twisted.internet import error, reactor
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/app/appservice.py b/synapse/app/appservice.py
index 4319ddce03..9a37384fb7 100644
--- a/synapse/app/appservice.py
+++ b/synapse/app/appservice.py
@@ -16,6 +16,9 @@
 import logging
 import sys
 
+from twisted.internet import defer, reactor
+from twisted.web.resource import NoResource
+
 import synapse
 from synapse import events
 from synapse.app import _base
@@ -36,8 +39,6 @@ from synapse.util.httpresourcetree import create_resource_tree
 from synapse.util.logcontext import LoggingContext, run_in_background
 from synapse.util.manhole import manhole
 from synapse.util.versionstring import get_version_string
-from twisted.internet import reactor, defer
-from twisted.web.resource import NoResource
 
 logger = logging.getLogger("synapse.app.appservice")
 
diff --git a/synapse/app/client_reader.py b/synapse/app/client_reader.py
index 654ddb8414..b0ea26dcb4 100644
--- a/synapse/app/client_reader.py
+++ b/synapse/app/client_reader.py
@@ -16,6 +16,9 @@
 import logging
 import sys
 
+from twisted.internet import reactor
+from twisted.web.resource import NoResource
+
 import synapse
 from synapse import events
 from synapse.app import _base
@@ -44,8 +47,6 @@ from synapse.util.httpresourcetree import create_resource_tree
 from synapse.util.logcontext import LoggingContext
 from synapse.util.manhole import manhole
 from synapse.util.versionstring import get_version_string
-from twisted.internet import reactor
-from twisted.web.resource import NoResource
 
 logger = logging.getLogger("synapse.app.client_reader")
 
diff --git a/synapse/app/event_creator.py b/synapse/app/event_creator.py
index 441467093a..374f115644 100644
--- a/synapse/app/event_creator.py
+++ b/synapse/app/event_creator.py
@@ -16,6 +16,9 @@
 import logging
 import sys
 
+from twisted.internet import reactor
+from twisted.web.resource import NoResource
+
 import synapse
 from synapse import events
 from synapse.app import _base
@@ -43,8 +46,10 @@ from synapse.replication.slave.storage.room import RoomStore
 from synapse.replication.slave.storage.transactions import TransactionStore
 from synapse.replication.tcp.client import ReplicationClientHandler
 from synapse.rest.client.v1.room import (
-    RoomSendEventRestServlet, RoomMembershipRestServlet, RoomStateEventRestServlet,
     JoinRoomAliasServlet,
+    RoomMembershipRestServlet,
+    RoomSendEventRestServlet,
+    RoomStateEventRestServlet,
 )
 from synapse.server import HomeServer
 from synapse.storage.engines import create_engine
@@ -52,8 +57,6 @@ from synapse.util.httpresourcetree import create_resource_tree
 from synapse.util.logcontext import LoggingContext
 from synapse.util.manhole import manhole
 from synapse.util.versionstring import get_version_string
-from twisted.internet import reactor
-from twisted.web.resource import NoResource
 
 logger = logging.getLogger("synapse.app.event_creator")
 
diff --git a/synapse/app/federation_reader.py b/synapse/app/federation_reader.py
index b2415cc671..7af00b8bcf 100644
--- a/synapse/app/federation_reader.py
+++ b/synapse/app/federation_reader.py
@@ -16,6 +16,9 @@
 import logging
 import sys
 
+from twisted.internet import reactor
+from twisted.web.resource import NoResource
+
 import synapse
 from synapse import events
 from synapse.api.urls import FEDERATION_PREFIX
@@ -41,8 +44,6 @@ from synapse.util.httpresourcetree import create_resource_tree
 from synapse.util.logcontext import LoggingContext
 from synapse.util.manhole import manhole
 from synapse.util.versionstring import get_version_string
-from twisted.internet import reactor
-from twisted.web.resource import NoResource
 
 logger = logging.getLogger("synapse.app.federation_reader")
 
diff --git a/synapse/app/federation_sender.py b/synapse/app/federation_sender.py
index 13d2b70053..18469013fa 100644
--- a/synapse/app/federation_sender.py
+++ b/synapse/app/federation_sender.py
@@ -16,6 +16,9 @@
 import logging
 import sys
 
+from twisted.internet import defer, reactor
+from twisted.web.resource import NoResource
+
 import synapse
 from synapse import events
 from synapse.app import _base
@@ -42,8 +45,6 @@ from synapse.util.httpresourcetree import create_resource_tree
 from synapse.util.logcontext import LoggingContext, run_in_background
 from synapse.util.manhole import manhole
 from synapse.util.versionstring import get_version_string
-from twisted.internet import defer, reactor
-from twisted.web.resource import NoResource
 
 logger = logging.getLogger("synapse.app.federation_sender")
 
diff --git a/synapse/app/frontend_proxy.py b/synapse/app/frontend_proxy.py
index e6db28333f..0d9abf3a24 100644
--- a/synapse/app/frontend_proxy.py
+++ b/synapse/app/frontend_proxy.py
@@ -16,6 +16,9 @@
 import logging
 import sys
 
+from twisted.internet import defer, reactor
+from twisted.web.resource import NoResource
+
 import synapse
 from synapse import events
 from synapse.api.errors import SynapseError
@@ -25,9 +28,7 @@ from synapse.config.homeserver import HomeServerConfig
 from synapse.config.logger import setup_logging
 from synapse.crypto import context_factory
 from synapse.http.server import JsonResource
-from synapse.http.servlet import (
-    RestServlet, parse_json_object_from_request,
-)
+from synapse.http.servlet import RestServlet, parse_json_object_from_request
 from synapse.http.site import SynapseSite
 from synapse.metrics import RegistryProxy
 from synapse.metrics.resource import METRICS_PREFIX, MetricsResource
@@ -45,8 +46,6 @@ from synapse.util.httpresourcetree import create_resource_tree
 from synapse.util.logcontext import LoggingContext
 from synapse.util.manhole import manhole
 from synapse.util.versionstring import get_version_string
-from twisted.internet import defer, reactor
-from twisted.web.resource import NoResource
 
 logger = logging.getLogger("synapse.app.frontend_proxy")
 
diff --git a/synapse/app/homeserver.py b/synapse/app/homeserver.py
index ae5fc751d5..14e6dca522 100755
--- a/synapse/app/homeserver.py
+++ b/synapse/app/homeserver.py
@@ -18,27 +18,39 @@ import logging
 import os
 import sys
 
+from twisted.application import service
+from twisted.internet import defer, reactor
+from twisted.web.resource import EncodingResourceWrapper, NoResource
+from twisted.web.server import GzipEncoderFactory
+from twisted.web.static import File
+
 import synapse
 import synapse.config.logger
 from synapse import events
-from synapse.api.urls import CONTENT_REPO_PREFIX, FEDERATION_PREFIX, \
-    LEGACY_MEDIA_PREFIX, MEDIA_PREFIX, SERVER_KEY_PREFIX, SERVER_KEY_V2_PREFIX, \
-    STATIC_PREFIX, WEB_CLIENT_PREFIX
+from synapse.api.urls import (
+    CONTENT_REPO_PREFIX,
+    FEDERATION_PREFIX,
+    LEGACY_MEDIA_PREFIX,
+    MEDIA_PREFIX,
+    SERVER_KEY_PREFIX,
+    SERVER_KEY_V2_PREFIX,
+    STATIC_PREFIX,
+    WEB_CLIENT_PREFIX,
+)
 from synapse.app import _base
-from synapse.app._base import quit_with_error, listen_ssl, listen_tcp
+from synapse.app._base import listen_ssl, listen_tcp, quit_with_error
 from synapse.config._base import ConfigError
 from synapse.config.homeserver import HomeServerConfig
 from synapse.crypto import context_factory
 from synapse.federation.transport.server import TransportLayerServer
-from synapse.module_api import ModuleApi
 from synapse.http.additional_resource import AdditionalResource
 from synapse.http.server import RootRedirect
 from synapse.http.site import SynapseSite
 from synapse.metrics import RegistryProxy
 from synapse.metrics.resource import METRICS_PREFIX, MetricsResource
-from synapse.python_dependencies import CONDITIONAL_REQUIREMENTS, \
-    check_requirements
-from synapse.replication.http import ReplicationRestResource, REPLICATION_PREFIX
+from synapse.module_api import ModuleApi
+from synapse.python_dependencies import CONDITIONAL_REQUIREMENTS, check_requirements
+from synapse.replication.http import REPLICATION_PREFIX, ReplicationRestResource
 from synapse.replication.tcp.resource import ReplicationStreamProtocolFactory
 from synapse.rest import ClientRestResource
 from synapse.rest.key.v1.server_key_resource import LocalKey
@@ -55,11 +67,6 @@ from synapse.util.manhole import manhole
 from synapse.util.module_loader import load_module
 from synapse.util.rlimit import change_resource_limit
 from synapse.util.versionstring import get_version_string
-from twisted.application import service
-from twisted.internet import defer, reactor
-from twisted.web.resource import EncodingResourceWrapper, NoResource
-from twisted.web.server import GzipEncoderFactory
-from twisted.web.static import File
 
 logger = logging.getLogger("synapse.app.homeserver")
 
diff --git a/synapse/app/media_repository.py b/synapse/app/media_repository.py
index 19a682cce3..749bbf37d0 100644
--- a/synapse/app/media_repository.py
+++ b/synapse/app/media_repository.py
@@ -16,11 +16,12 @@
 import logging
 import sys
 
+from twisted.internet import reactor
+from twisted.web.resource import NoResource
+
 import synapse
 from synapse import events
-from synapse.api.urls import (
-    CONTENT_REPO_PREFIX, LEGACY_MEDIA_PREFIX, MEDIA_PREFIX
-)
+from synapse.api.urls import CONTENT_REPO_PREFIX, LEGACY_MEDIA_PREFIX, MEDIA_PREFIX
 from synapse.app import _base
 from synapse.config._base import ConfigError
 from synapse.config.homeserver import HomeServerConfig
@@ -43,8 +44,6 @@ from synapse.util.httpresourcetree import create_resource_tree
 from synapse.util.logcontext import LoggingContext
 from synapse.util.manhole import manhole
 from synapse.util.versionstring import get_version_string
-from twisted.internet import reactor
-from twisted.web.resource import NoResource
 
 logger = logging.getLogger("synapse.app.media_repository")
 
diff --git a/synapse/app/pusher.py b/synapse/app/pusher.py
index 13cfbd08b0..9295a51d5b 100644
--- a/synapse/app/pusher.py
+++ b/synapse/app/pusher.py
@@ -16,6 +16,9 @@
 import logging
 import sys
 
+from twisted.internet import defer, reactor
+from twisted.web.resource import NoResource
+
 import synapse
 from synapse import events
 from synapse.app import _base
@@ -37,8 +40,6 @@ from synapse.util.httpresourcetree import create_resource_tree
 from synapse.util.logcontext import LoggingContext, run_in_background
 from synapse.util.manhole import manhole
 from synapse.util.versionstring import get_version_string
-from twisted.internet import defer, reactor
-from twisted.web.resource import NoResource
 
 logger = logging.getLogger("synapse.app.pusher")
 
diff --git a/synapse/app/synchrotron.py b/synapse/app/synchrotron.py
index 67a2d2b7db..4c097a5d2c 100644
--- a/synapse/app/synchrotron.py
+++ b/synapse/app/synchrotron.py
@@ -17,6 +17,11 @@ import contextlib
 import logging
 import sys
 
+from six import iteritems
+
+from twisted.internet import defer, reactor
+from twisted.web.resource import NoResource
+
 import synapse
 from synapse.api.constants import EventTypes
 from synapse.app import _base
@@ -36,12 +41,12 @@ from synapse.replication.slave.storage.deviceinbox import SlavedDeviceInboxStore
 from synapse.replication.slave.storage.devices import SlavedDeviceStore
 from synapse.replication.slave.storage.events import SlavedEventStore
 from synapse.replication.slave.storage.filtering import SlavedFilteringStore
+from synapse.replication.slave.storage.groups import SlavedGroupServerStore
 from synapse.replication.slave.storage.presence import SlavedPresenceStore
 from synapse.replication.slave.storage.push_rule import SlavedPushRuleStore
 from synapse.replication.slave.storage.receipts import SlavedReceiptsStore
 from synapse.replication.slave.storage.registration import SlavedRegistrationStore
 from synapse.replication.slave.storage.room import RoomStore
-from synapse.replication.slave.storage.groups import SlavedGroupServerStore
 from synapse.replication.tcp.client import ReplicationClientHandler
 from synapse.rest.client.v1 import events
 from synapse.rest.client.v1.initial_sync import InitialSyncRestServlet
@@ -56,10 +61,6 @@ from synapse.util.logcontext import LoggingContext, run_in_background
 from synapse.util.manhole import manhole
 from synapse.util.stringutils import random_string
 from synapse.util.versionstring import get_version_string
-from twisted.internet import defer, reactor
-from twisted.web.resource import NoResource
-
-from six import iteritems
 
 logger = logging.getLogger("synapse.app.synchrotron")
 
diff --git a/synapse/app/synctl.py b/synapse/app/synctl.py
index 8c525459c7..74093004c2 100755
--- a/synapse/app/synctl.py
+++ b/synapse/app/synctl.py
@@ -16,16 +16,17 @@
 
 import argparse
 import collections
+import errno
 import glob
 import os
 import os.path
 import signal
 import subprocess
 import sys
-import yaml
-import errno
 import time
 
+import yaml
+
 SYNAPSE = [sys.executable, "-B", "-m", "synapse.app.homeserver"]
 
 GREEN = "\x1b[1;32m"
diff --git a/synapse/app/user_dir.py b/synapse/app/user_dir.py
index f5726e3df6..637a89530a 100644
--- a/synapse/app/user_dir.py
+++ b/synapse/app/user_dir.py
@@ -17,6 +17,9 @@
 import logging
 import sys
 
+from twisted.internet import defer, reactor
+from twisted.web.resource import NoResource
+
 import synapse
 from synapse import events
 from synapse.app import _base
@@ -43,8 +46,6 @@ from synapse.util.httpresourcetree import create_resource_tree
 from synapse.util.logcontext import LoggingContext, run_in_background
 from synapse.util.manhole import manhole
 from synapse.util.versionstring import get_version_string
-from twisted.internet import reactor, defer
-from twisted.web.resource import NoResource
 
 logger = logging.getLogger("synapse.app.user_dir")
 
diff --git a/synapse/appservice/__init__.py b/synapse/appservice/__init__.py
index 328cbfa284..57ed8a3ca2 100644
--- a/synapse/appservice/__init__.py
+++ b/synapse/appservice/__init__.py
@@ -12,17 +12,17 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-from synapse.api.constants import EventTypes
-from synapse.util.caches.descriptors import cachedInlineCallbacks
-from synapse.types import GroupID, get_domain_from_id
-
-from twisted.internet import defer
-
 import logging
 import re
 
 from six import string_types
 
+from twisted.internet import defer
+
+from synapse.api.constants import EventTypes
+from synapse.types import GroupID, get_domain_from_id
+from synapse.util.caches.descriptors import cachedInlineCallbacks
+
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/appservice/api.py b/synapse/appservice/api.py
index 47251fb6ad..6980e5890e 100644
--- a/synapse/appservice/api.py
+++ b/synapse/appservice/api.py
@@ -12,20 +12,20 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-from twisted.internet import defer
-
-from synapse.api.constants import ThirdPartyEntityKind
-from synapse.api.errors import CodeMessageException
-from synapse.http.client import SimpleHttpClient
-from synapse.events.utils import serialize_event
-from synapse.util.caches.response_cache import ResponseCache
-from synapse.types import ThirdPartyInstanceID
-
 import logging
 import urllib
 
 from prometheus_client import Counter
 
+from twisted.internet import defer
+
+from synapse.api.constants import ThirdPartyEntityKind
+from synapse.api.errors import CodeMessageException
+from synapse.events.utils import serialize_event
+from synapse.http.client import SimpleHttpClient
+from synapse.types import ThirdPartyInstanceID
+from synapse.util.caches.response_cache import ResponseCache
+
 logger = logging.getLogger(__name__)
 
 sent_transactions_counter = Counter(
diff --git a/synapse/appservice/scheduler.py b/synapse/appservice/scheduler.py
index 6eddbc0828..2430814796 100644
--- a/synapse/appservice/scheduler.py
+++ b/synapse/appservice/scheduler.py
@@ -48,14 +48,14 @@ UP & quit           +---------- YES                       SUCCESS
 This is all tied together by the AppServiceScheduler which DIs the required
 components.
 """
+import logging
+
 from twisted.internet import defer
 
 from synapse.appservice import ApplicationServiceState
 from synapse.util.logcontext import run_in_background
 from synapse.util.metrics import Measure
 
-import logging
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/config/_base.py b/synapse/config/_base.py
index b748ed2b0a..3d2e90dd5b 100644
--- a/synapse/config/_base.py
+++ b/synapse/config/_base.py
@@ -16,11 +16,12 @@
 import argparse
 import errno
 import os
-import yaml
 from textwrap import dedent
 
 from six import integer_types
 
+import yaml
+
 
 class ConfigError(Exception):
     pass
diff --git a/synapse/config/api.py b/synapse/config/api.py
index 20ba33226a..403d96ba76 100644
--- a/synapse/config/api.py
+++ b/synapse/config/api.py
@@ -12,10 +12,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import Config
-
 from synapse.api.constants import EventTypes
 
+from ._base import Config
+
 
 class ApiConfig(Config):
 
diff --git a/synapse/config/appservice.py b/synapse/config/appservice.py
index 0c27bb2fa7..3b161d708a 100644
--- a/synapse/config/appservice.py
+++ b/synapse/config/appservice.py
@@ -12,19 +12,19 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import Config, ConfigError
-
-from synapse.appservice import ApplicationService
-from synapse.types import UserID
-
-from netaddr import IPSet
-
-import yaml
 import logging
 
 from six import string_types
 from six.moves.urllib import parse as urlparse
 
+import yaml
+from netaddr import IPSet
+
+from synapse.appservice import ApplicationService
+from synapse.types import UserID
+
+from ._base import Config, ConfigError
+
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/config/homeserver.py b/synapse/config/homeserver.py
index 1dea2ad024..2fd9c48abf 100644
--- a/synapse/config/homeserver.py
+++ b/synapse/config/homeserver.py
@@ -13,32 +13,32 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-from .tls import TlsConfig
-from .server import ServerConfig
-from .logger import LoggingConfig
-from .database import DatabaseConfig
-from .ratelimiting import RatelimitConfig
-from .repository import ContentRepositoryConfig
-from .captcha import CaptchaConfig
-from .voip import VoipConfig
-from .registration import RegistrationConfig
-from .metrics import MetricsConfig
 from .api import ApiConfig
 from .appservice import AppServiceConfig
-from .key import KeyConfig
-from .saml2 import SAML2Config
+from .captcha import CaptchaConfig
 from .cas import CasConfig
-from .password import PasswordConfig
-from .jwt import JWTConfig
-from .password_auth_providers import PasswordAuthProviderConfig
-from .emailconfig import EmailConfig
-from .workers import WorkerConfig
-from .push import PushConfig
-from .spam_checker import SpamCheckerConfig
-from .groups import GroupsConfig
-from .user_directory import UserDirectoryConfig
 from .consent_config import ConsentConfig
+from .database import DatabaseConfig
+from .emailconfig import EmailConfig
+from .groups import GroupsConfig
+from .jwt import JWTConfig
+from .key import KeyConfig
+from .logger import LoggingConfig
+from .metrics import MetricsConfig
+from .password import PasswordConfig
+from .password_auth_providers import PasswordAuthProviderConfig
+from .push import PushConfig
+from .ratelimiting import RatelimitConfig
+from .registration import RegistrationConfig
+from .repository import ContentRepositoryConfig
+from .saml2 import SAML2Config
+from .server import ServerConfig
 from .server_notices_config import ServerNoticesConfig
+from .spam_checker import SpamCheckerConfig
+from .tls import TlsConfig
+from .user_directory import UserDirectoryConfig
+from .voip import VoipConfig
+from .workers import WorkerConfig
 
 
 class HomeServerConfig(TlsConfig, ServerConfig, DatabaseConfig, LoggingConfig,
diff --git a/synapse/config/jwt.py b/synapse/config/jwt.py
index 47f145c589..51e7f7e003 100644
--- a/synapse/config/jwt.py
+++ b/synapse/config/jwt.py
@@ -15,7 +15,6 @@
 
 from ._base import Config, ConfigError
 
-
 MISSING_JWT = (
     """Missing jwt library. This is required for jwt login.
 
diff --git a/synapse/config/key.py b/synapse/config/key.py
index d1382ad9ac..279c47bb48 100644
--- a/synapse/config/key.py
+++ b/synapse/config/key.py
@@ -13,21 +13,24 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import Config, ConfigError
-
-from synapse.util.stringutils import random_string
-from signedjson.key import (
-    generate_signing_key, is_signing_algorithm_supported,
-    decode_signing_key_base64, decode_verify_key_bytes,
-    read_signing_keys, write_signing_keys, NACL_ED25519
-)
-from unpaddedbase64 import decode_base64
-from synapse.util.stringutils import random_string_with_symbols
-
-import os
 import hashlib
 import logging
+import os
 
+from signedjson.key import (
+    NACL_ED25519,
+    decode_signing_key_base64,
+    decode_verify_key_bytes,
+    generate_signing_key,
+    is_signing_algorithm_supported,
+    read_signing_keys,
+    write_signing_keys,
+)
+from unpaddedbase64 import decode_base64
+
+from synapse.util.stringutils import random_string, random_string_with_symbols
+
+from ._base import Config, ConfigError
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/config/logger.py b/synapse/config/logger.py
index 557c270fbe..a87b11a1df 100644
--- a/synapse/config/logger.py
+++ b/synapse/config/logger.py
@@ -16,15 +16,17 @@ import logging
 import logging.config
 import os
 import signal
-from string import Template
 import sys
+from string import Template
+
+import yaml
 
 from twisted.logger import STDLibLogObserver, globalLogBeginner
-import yaml
 
 import synapse
 from synapse.util.logcontext import LoggingContextFilter
 from synapse.util.versionstring import get_version_string
+
 from ._base import Config
 
 DEFAULT_LOG_CONFIG = Template("""
diff --git a/synapse/config/password_auth_providers.py b/synapse/config/password_auth_providers.py
index 6602c5b4c7..f4066abc28 100644
--- a/synapse/config/password_auth_providers.py
+++ b/synapse/config/password_auth_providers.py
@@ -13,10 +13,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import Config
-
 from synapse.util.module_loader import load_module
 
+from ._base import Config
+
 LDAP_PROVIDER = 'ldap_auth_provider.LdapAuthProvider'
 
 
diff --git a/synapse/config/registration.py b/synapse/config/registration.py
index c5384b3ad4..0fb964eb67 100644
--- a/synapse/config/registration.py
+++ b/synapse/config/registration.py
@@ -13,11 +13,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import Config
+from distutils.util import strtobool
 
 from synapse.util.stringutils import random_string_with_symbols
 
-from distutils.util import strtobool
+from ._base import Config
 
 
 class RegistrationConfig(Config):
diff --git a/synapse/config/repository.py b/synapse/config/repository.py
index 81ecf9778c..fc909c1fac 100644
--- a/synapse/config/repository.py
+++ b/synapse/config/repository.py
@@ -13,11 +13,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import Config, ConfigError
 from collections import namedtuple
 
 from synapse.util.module_loader import load_module
 
+from ._base import Config, ConfigError
 
 MISSING_NETADDR = (
     "Missing netaddr library. This is required for URL preview API."
diff --git a/synapse/config/server.py b/synapse/config/server.py
index 71fd51e4bc..18102656b0 100644
--- a/synapse/config/server.py
+++ b/synapse/config/server.py
@@ -17,6 +17,7 @@
 import logging
 
 from synapse.http.endpoint import parse_and_validate_server_name
+
 from ._base import Config, ConfigError
 
 logger = logging.Logger(__name__)
diff --git a/synapse/config/server_notices_config.py b/synapse/config/server_notices_config.py
index be1d1f762c..3c39850ac6 100644
--- a/synapse/config/server_notices_config.py
+++ b/synapse/config/server_notices_config.py
@@ -12,9 +12,10 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-from ._base import Config
 from synapse.types import UserID
 
+from ._base import Config
+
 DEFAULT_CONFIG = """\
 # Server Notices room configuration
 #
diff --git a/synapse/config/tls.py b/synapse/config/tls.py
index b66154bc7c..fef1ea99cb 100644
--- a/synapse/config/tls.py
+++ b/synapse/config/tls.py
@@ -13,14 +13,15 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import Config
+import os
+import subprocess
+from hashlib import sha256
+
+from unpaddedbase64 import encode_base64
 
 from OpenSSL import crypto
-import subprocess
-import os
 
-from hashlib import sha256
-from unpaddedbase64 import encode_base64
+from ._base import Config
 
 GENERATE_DH_PARAMS = False
 
diff --git a/synapse/crypto/context_factory.py b/synapse/crypto/context_factory.py
index 0397f73ab4..a1e1d0d33a 100644
--- a/synapse/crypto/context_factory.py
+++ b/synapse/crypto/context_factory.py
@@ -12,12 +12,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import ssl
-from OpenSSL import SSL, crypto
-from twisted.internet._sslverify import _defaultCurveName
-
 import logging
 
+from OpenSSL import SSL, crypto
+from twisted.internet import ssl
+from twisted.internet._sslverify import _defaultCurveName
+
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/crypto/event_signing.py b/synapse/crypto/event_signing.py
index aaa3efaca3..8774b28967 100644
--- a/synapse/crypto/event_signing.py
+++ b/synapse/crypto/event_signing.py
@@ -15,16 +15,16 @@
 # limitations under the License.
 
 
-from synapse.api.errors import SynapseError, Codes
-from synapse.events.utils import prune_event
-
-from canonicaljson import encode_canonical_json
-from unpaddedbase64 import encode_base64, decode_base64
-from signedjson.sign import sign_json
-
 import hashlib
 import logging
 
+from canonicaljson import encode_canonical_json
+from signedjson.sign import sign_json
+from unpaddedbase64 import decode_base64, encode_base64
+
+from synapse.api.errors import Codes, SynapseError
+from synapse.events.utils import prune_event
+
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/crypto/keyclient.py b/synapse/crypto/keyclient.py
index 2a0eddbea1..668b4f517d 100644
--- a/synapse/crypto/keyclient.py
+++ b/synapse/crypto/keyclient.py
@@ -13,14 +13,16 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.util import logcontext
-from twisted.web.http import HTTPClient
-from twisted.internet.protocol import Factory
-from twisted.internet import defer, reactor
-from synapse.http.endpoint import matrix_federation_endpoint
-from canonicaljson import json
 import logging
 
+from canonicaljson import json
+
+from twisted.internet import defer, reactor
+from twisted.internet.protocol import Factory
+from twisted.web.http import HTTPClient
+
+from synapse.http.endpoint import matrix_federation_endpoint
+from synapse.util import logcontext
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/crypto/keyring.py b/synapse/crypto/keyring.py
index 9b17ef0a08..e95b9fb43e 100644
--- a/synapse/crypto/keyring.py
+++ b/synapse/crypto/keyring.py
@@ -14,9 +14,31 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import hashlib
+import logging
+import urllib
+from collections import namedtuple
+
+from signedjson.key import (
+    decode_verify_key_bytes,
+    encode_verify_key_base64,
+    is_signing_algorithm_supported,
+)
+from signedjson.sign import (
+    SignatureVerifyException,
+    encode_canonical_json,
+    sign_json,
+    signature_ids,
+    verify_signed_json,
+)
+from unpaddedbase64 import decode_base64, encode_base64
+
+from OpenSSL import crypto
+from twisted.internet import defer
+
+from synapse.api.errors import Codes, SynapseError
 from synapse.crypto.keyclient import fetch_server_key
-from synapse.api.errors import SynapseError, Codes
-from synapse.util import unwrapFirstError, logcontext
+from synapse.util import logcontext, unwrapFirstError
 from synapse.util.logcontext import (
     PreserveLoggingContext,
     preserve_fn,
@@ -24,26 +46,6 @@ from synapse.util.logcontext import (
 )
 from synapse.util.metrics import Measure
 
-from twisted.internet import defer
-
-from signedjson.sign import (
-    verify_signed_json, signature_ids, sign_json, encode_canonical_json,
-    SignatureVerifyException,
-)
-from signedjson.key import (
-    is_signing_algorithm_supported, decode_verify_key_bytes,
-    encode_verify_key_base64,
-)
-from unpaddedbase64 import decode_base64, encode_base64
-
-from OpenSSL import crypto
-
-from collections import namedtuple
-import urllib
-import hashlib
-import logging
-
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/event_auth.py b/synapse/event_auth.py
index cdf99fd140..b32f64e729 100644
--- a/synapse/event_auth.py
+++ b/synapse/event_auth.py
@@ -17,11 +17,11 @@ import logging
 
 from canonicaljson import encode_canonical_json
 from signedjson.key import decode_verify_key_bytes
-from signedjson.sign import verify_signed_json, SignatureVerifyException
+from signedjson.sign import SignatureVerifyException, verify_signed_json
 from unpaddedbase64 import decode_base64
 
-from synapse.api.constants import EventTypes, Membership, JoinRules
-from synapse.api.errors import AuthError, SynapseError, EventSizeError
+from synapse.api.constants import EventTypes, JoinRules, Membership
+from synapse.api.errors import AuthError, EventSizeError, SynapseError
 from synapse.types import UserID, get_domain_from_id
 
 logger = logging.getLogger(__name__)
diff --git a/synapse/events/__init__.py b/synapse/events/__init__.py
index cb08da4984..51f9084b90 100644
--- a/synapse/events/__init__.py
+++ b/synapse/events/__init__.py
@@ -13,9 +13,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.util.frozenutils import freeze
 from synapse.util.caches import intern_dict
-
+from synapse.util.frozenutils import freeze
 
 # Whether we should use frozen_dict in FrozenEvent. Using frozen_dicts prevents
 # bugs where we accidentally share e.g. signature dicts. However, converting
diff --git a/synapse/events/builder.py b/synapse/events/builder.py
index 13fbba68c0..e662eaef10 100644
--- a/synapse/events/builder.py
+++ b/synapse/events/builder.py
@@ -13,13 +13,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from . import EventBase, FrozenEvent, _event_dict_property
+import copy
 
 from synapse.types import EventID
-
 from synapse.util.stringutils import random_string
 
-import copy
+from . import EventBase, FrozenEvent, _event_dict_property
 
 
 class EventBuilder(EventBase):
diff --git a/synapse/events/snapshot.py b/synapse/events/snapshot.py
index 8e684d91b5..bcd9bb5946 100644
--- a/synapse/events/snapshot.py
+++ b/synapse/events/snapshot.py
@@ -13,10 +13,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer
-
 from frozendict import frozendict
 
+from twisted.internet import defer
+
 
 class EventContext(object):
     """
diff --git a/synapse/events/utils.py b/synapse/events/utils.py
index 29ae086786..652941ca0d 100644
--- a/synapse/events/utils.py
+++ b/synapse/events/utils.py
@@ -13,15 +13,16 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.api.constants import EventTypes
-from . import EventBase
-
-from frozendict import frozendict
-
 import re
 
 from six import string_types
 
+from frozendict import frozendict
+
+from synapse.api.constants import EventTypes
+
+from . import EventBase
+
 # Split strings on "." but not "\." This uses a negative lookbehind assertion for '\'
 # (?<!stuff) matches if the current position in the string is not preceded
 # by a match for 'stuff'.
diff --git a/synapse/events/validator.py b/synapse/events/validator.py
index e0e5bf818c..cf184748a1 100644
--- a/synapse/events/validator.py
+++ b/synapse/events/validator.py
@@ -13,12 +13,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.types import EventID, RoomID, UserID
-from synapse.api.errors import SynapseError
-from synapse.api.constants import EventTypes, Membership
-
 from six import string_types
 
+from synapse.api.constants import EventTypes, Membership
+from synapse.api.errors import SynapseError
+from synapse.types import EventID, RoomID, UserID
+
 
 class EventValidator(object):
 
diff --git a/synapse/federation/federation_base.py b/synapse/federation/federation_base.py
index 4cc98a3fe8..f0c7a06718 100644
--- a/synapse/federation/federation_base.py
+++ b/synapse/federation/federation_base.py
@@ -16,14 +16,15 @@ import logging
 
 import six
 
+from twisted.internet import defer
+
 from synapse.api.constants import MAX_DEPTH
-from synapse.api.errors import SynapseError, Codes
+from synapse.api.errors import Codes, SynapseError
 from synapse.crypto.event_signing import check_event_content_hash
 from synapse.events import FrozenEvent
 from synapse.events.utils import prune_event
 from synapse.http.servlet import assert_params_in_request
-from synapse.util import unwrapFirstError, logcontext
-from twisted.internet import defer
+from synapse.util import logcontext, unwrapFirstError
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/federation/federation_client.py b/synapse/federation/federation_client.py
index 87a92f6ea9..62d7ed13cf 100644
--- a/synapse/federation/federation_client.py
+++ b/synapse/federation/federation_client.py
@@ -21,25 +21,25 @@ import random
 
 from six.moves import range
 
+from prometheus_client import Counter
+
 from twisted.internet import defer
 
 from synapse.api.constants import Membership
 from synapse.api.errors import (
-    CodeMessageException, HttpResponseException, SynapseError, FederationDeniedError
+    CodeMessageException,
+    FederationDeniedError,
+    HttpResponseException,
+    SynapseError,
 )
 from synapse.events import builder
-from synapse.federation.federation_base import (
-    FederationBase,
-    event_from_pdu_json,
-)
+from synapse.federation.federation_base import FederationBase, event_from_pdu_json
 from synapse.util import logcontext, unwrapFirstError
 from synapse.util.caches.expiringcache import ExpiringCache
 from synapse.util.logcontext import make_deferred_yieldable, run_in_background
 from synapse.util.logutils import log_function
 from synapse.util.retryutils import NotRetryingDestination
 
-from prometheus_client import Counter
-
 logger = logging.getLogger(__name__)
 
 sent_queries_counter = Counter("synapse_federation_client_sent_queries", "", ["type"])
diff --git a/synapse/federation/federation_server.py b/synapse/federation/federation_server.py
index 591d0026bf..48f26db67c 100644
--- a/synapse/federation/federation_server.py
+++ b/synapse/federation/federation_server.py
@@ -16,19 +16,19 @@
 import logging
 import re
 
-from canonicaljson import json
 import six
+from six import iteritems
+
+from canonicaljson import json
+from prometheus_client import Counter
+
 from twisted.internet import defer
 from twisted.internet.abstract import isIPAddress
 
 from synapse.api.constants import EventTypes
-from synapse.api.errors import AuthError, FederationError, SynapseError, NotFoundError
+from synapse.api.errors import AuthError, FederationError, NotFoundError, SynapseError
 from synapse.crypto.event_signing import compute_event_signature
-from synapse.federation.federation_base import (
-    FederationBase,
-    event_from_pdu_json,
-)
-
+from synapse.federation.federation_base import FederationBase, event_from_pdu_json
 from synapse.federation.persistence import TransactionActions
 from synapse.federation.units import Edu, Transaction
 from synapse.http.endpoint import parse_server_name
@@ -37,10 +37,6 @@ from synapse.util import async
 from synapse.util.caches.response_cache import ResponseCache
 from synapse.util.logutils import log_function
 
-from prometheus_client import Counter
-
-from six import iteritems
-
 # when processing incoming transactions, we try to handle multiple rooms in
 # parallel, up to this limit.
 TRANSACTION_CONCURRENCY_LIMIT = 10
diff --git a/synapse/federation/persistence.py b/synapse/federation/persistence.py
index 84dc606673..9146215c21 100644
--- a/synapse/federation/persistence.py
+++ b/synapse/federation/persistence.py
@@ -19,13 +19,12 @@ package.
 These actions are mostly only used by the :py:mod:`.replication` module.
 """
 
+import logging
+
 from twisted.internet import defer
 
 from synapse.util.logutils import log_function
 
-import logging
-
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/federation/send_queue.py b/synapse/federation/send_queue.py
index 1d5c0f3797..5157c3860d 100644
--- a/synapse/federation/send_queue.py
+++ b/synapse/federation/send_queue.py
@@ -29,18 +29,18 @@ dead worker doesn't cause the queues to grow limitlessly.
 Events are replicated via a separate events stream.
 """
 
-from .units import Edu
-
-from synapse.storage.presence import UserPresenceState
-from synapse.util.metrics import Measure
-from synapse.metrics import LaterGauge
-
-from sortedcontainers import SortedDict
+import logging
 from collections import namedtuple
 
-import logging
+from six import iteritems, itervalues
 
-from six import itervalues, iteritems
+from sortedcontainers import SortedDict
+
+from synapse.metrics import LaterGauge
+from synapse.storage.presence import UserPresenceState
+from synapse.util.metrics import Measure
+
+from .units import Edu
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/federation/transaction_queue.py b/synapse/federation/transaction_queue.py
index b9d0639a1b..979545d613 100644
--- a/synapse/federation/transaction_queue.py
+++ b/synapse/federation/transaction_queue.py
@@ -13,31 +13,29 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import datetime
-
-from twisted.internet import defer
-
-from .persistence import TransactionActions
-from .units import Transaction, Edu
-
-from synapse.api.errors import HttpResponseException, FederationDeniedError
-from synapse.util import logcontext, PreserveLoggingContext
-from synapse.util.retryutils import NotRetryingDestination, get_retry_limiter
-from synapse.util.metrics import measure_func
-from synapse.handlers.presence import format_user_presence_state, get_interested_remotes
-import synapse.metrics
-from synapse.metrics import LaterGauge
-from synapse.metrics import (
-    sent_edus_counter,
-    sent_transactions_counter,
-    events_processed_counter,
-)
-
-from prometheus_client import Counter
+import logging
 
 from six import itervalues
 
-import logging
+from prometheus_client import Counter
 
+from twisted.internet import defer
+
+import synapse.metrics
+from synapse.api.errors import FederationDeniedError, HttpResponseException
+from synapse.handlers.presence import format_user_presence_state, get_interested_remotes
+from synapse.metrics import (
+    LaterGauge,
+    events_processed_counter,
+    sent_edus_counter,
+    sent_transactions_counter,
+)
+from synapse.util import PreserveLoggingContext, logcontext
+from synapse.util.metrics import measure_func
+from synapse.util.retryutils import NotRetryingDestination, get_retry_limiter
+
+from .persistence import TransactionActions
+from .units import Edu, Transaction
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/federation/transport/client.py b/synapse/federation/transport/client.py
index 6db8efa6dd..4529d454af 100644
--- a/synapse/federation/transport/client.py
+++ b/synapse/federation/transport/client.py
@@ -14,15 +14,14 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer
-from synapse.api.constants import Membership
-
-from synapse.api.urls import FEDERATION_PREFIX as PREFIX
-from synapse.util.logutils import log_function
-
 import logging
 import urllib
 
+from twisted.internet import defer
+
+from synapse.api.constants import Membership
+from synapse.api.urls import FEDERATION_PREFIX as PREFIX
+from synapse.util.logutils import log_function
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/federation/transport/server.py b/synapse/federation/transport/server.py
index c6d98d35cb..c9beca27c2 100644
--- a/synapse/federation/transport/server.py
+++ b/synapse/federation/transport/server.py
@@ -14,26 +14,27 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer
-
-from synapse.api.urls import FEDERATION_PREFIX as PREFIX
-from synapse.api.errors import Codes, SynapseError, FederationDeniedError
-from synapse.http.endpoint import parse_and_validate_server_name
-from synapse.http.server import JsonResource
-from synapse.http.servlet import (
-    parse_json_object_from_request, parse_integer_from_args, parse_string_from_args,
-    parse_boolean_from_args,
-)
-from synapse.util.ratelimitutils import FederationRateLimiter
-from synapse.util.versionstring import get_version_string
-from synapse.util.logcontext import run_in_background
-from synapse.types import ThirdPartyInstanceID, get_domain_from_id
-
 import functools
 import logging
 import re
-import synapse
 
+from twisted.internet import defer
+
+import synapse
+from synapse.api.errors import Codes, FederationDeniedError, SynapseError
+from synapse.api.urls import FEDERATION_PREFIX as PREFIX
+from synapse.http.endpoint import parse_and_validate_server_name
+from synapse.http.server import JsonResource
+from synapse.http.servlet import (
+    parse_boolean_from_args,
+    parse_integer_from_args,
+    parse_json_object_from_request,
+    parse_string_from_args,
+)
+from synapse.types import ThirdPartyInstanceID, get_domain_from_id
+from synapse.util.logcontext import run_in_background
+from synapse.util.ratelimitutils import FederationRateLimiter
+from synapse.util.versionstring import get_version_string
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/federation/units.py b/synapse/federation/units.py
index 01c5b8fe17..bb1b3b13f7 100644
--- a/synapse/federation/units.py
+++ b/synapse/federation/units.py
@@ -17,10 +17,9 @@
 server protocol.
 """
 
-from synapse.util.jsonobject import JsonEncodedObject
-
 import logging
 
+from synapse.util.jsonobject import JsonEncodedObject
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/groups/attestations.py b/synapse/groups/attestations.py
index 6f11fa374b..47452700a8 100644
--- a/synapse/groups/attestations.py
+++ b/synapse/groups/attestations.py
@@ -23,9 +23,9 @@ If a user leaves (or gets kicked out of) a group, either side can still use
 their attestation to "prove" their membership, until the attestation expires.
 Therefore attestations shouldn't be relied on to prove membership in important
 cases, but can for less important situtations, e.g. showing a users membership
-of groups on their profile, showing flairs, etc.abs
+of groups on their profile, showing flairs, etc.
 
-An attestsation is a signed blob of json that looks like:
+An attestation is a signed blob of json that looks like:
 
     {
         "user_id": "@foo:a.example.com",
@@ -38,15 +38,14 @@ An attestsation is a signed blob of json that looks like:
 import logging
 import random
 
+from signedjson.sign import sign_json
+
 from twisted.internet import defer
 
 from synapse.api.errors import SynapseError
 from synapse.types import get_domain_from_id
 from synapse.util.logcontext import run_in_background
 
-from signedjson.sign import sign_json
-
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/groups/groups_server.py b/synapse/groups/groups_server.py
index 62d20ad130..633c865ed8 100644
--- a/synapse/groups/groups_server.py
+++ b/synapse/groups/groups_server.py
@@ -16,11 +16,12 @@
 
 import logging
 
-from synapse.api.errors import SynapseError
-from synapse.types import GroupID, RoomID, UserID, get_domain_from_id
+from six import string_types
+
 from twisted.internet import defer
 
-from six import string_types
+from synapse.api.errors import SynapseError
+from synapse.types import GroupID, RoomID, UserID, get_domain_from_id
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/handlers/__init__.py b/synapse/handlers/__init__.py
index d358842b3e..4b9923d8c0 100644
--- a/synapse/handlers/__init__.py
+++ b/synapse/handlers/__init__.py
@@ -13,13 +13,13 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from .admin import AdminHandler
+from .directory import DirectoryHandler
+from .federation import FederationHandler
+from .identity import IdentityHandler
+from .message import MessageHandler
 from .register import RegistrationHandler
 from .room import RoomContextHandler
-from .message import MessageHandler
-from .federation import FederationHandler
-from .directory import DirectoryHandler
-from .admin import AdminHandler
-from .identity import IdentityHandler
 from .search import SearchHandler
 
 
diff --git a/synapse/handlers/_base.py b/synapse/handlers/_base.py
index 2d1db0c245..b6a8b3aa3b 100644
--- a/synapse/handlers/_base.py
+++ b/synapse/handlers/_base.py
@@ -18,11 +18,10 @@ import logging
 from twisted.internet import defer
 
 import synapse.types
-from synapse.api.constants import Membership, EventTypes
+from synapse.api.constants import EventTypes, Membership
 from synapse.api.errors import LimitExceededError
 from synapse.types import UserID
 
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/handlers/admin.py b/synapse/handlers/admin.py
index f36b358b45..5d629126fc 100644
--- a/synapse/handlers/admin.py
+++ b/synapse/handlers/admin.py
@@ -13,12 +13,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import logging
+
 from twisted.internet import defer
 
 from ._base import BaseHandler
 
-import logging
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/handlers/appservice.py b/synapse/handlers/appservice.py
index 1c29c43a83..ec9fe01a5a 100644
--- a/synapse/handlers/appservice.py
+++ b/synapse/handlers/appservice.py
@@ -13,19 +13,18 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer
+import logging
 
 from six import itervalues
 
-import synapse
-from synapse.api.constants import EventTypes
-from synapse.util.metrics import Measure
-from synapse.util.logcontext import (
-    make_deferred_yieldable, run_in_background,
-)
 from prometheus_client import Counter
 
-import logging
+from twisted.internet import defer
+
+import synapse
+from synapse.api.constants import EventTypes
+from synapse.util.logcontext import make_deferred_yieldable, run_in_background
+from synapse.util.metrics import Measure
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/handlers/auth.py b/synapse/handlers/auth.py
index cbef1f2770..402e44cdef 100644
--- a/synapse/handlers/auth.py
+++ b/synapse/handlers/auth.py
@@ -14,14 +14,24 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer, threads
+import logging
 
+import attr
+import bcrypt
+import pymacaroons
 from canonicaljson import json
 
-from ._base import BaseHandler
+from twisted.internet import defer, threads
+from twisted.web.client import PartialDownloadError
+
+import synapse.util.stringutils as stringutils
 from synapse.api.constants import LoginType
 from synapse.api.errors import (
-    AuthError, Codes, InteractiveAuthIncompleteError, LoginError, StoreError,
+    AuthError,
+    Codes,
+    InteractiveAuthIncompleteError,
+    LoginError,
+    StoreError,
     SynapseError,
 )
 from synapse.module_api import ModuleApi
@@ -29,15 +39,7 @@ from synapse.types import UserID
 from synapse.util.caches.expiringcache import ExpiringCache
 from synapse.util.logcontext import make_deferred_yieldable
 
-from twisted.web.client import PartialDownloadError
-
-import logging
-import bcrypt
-import pymacaroons
-import attr
-
-import synapse.util.stringutils as stringutils
-
+from ._base import BaseHandler
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/handlers/deactivate_account.py b/synapse/handlers/deactivate_account.py
index a84b7b8b80..b3c5a9ee64 100644
--- a/synapse/handlers/deactivate_account.py
+++ b/synapse/handlers/deactivate_account.py
@@ -12,14 +12,15 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+import logging
+
 from twisted.internet import defer
 
-from ._base import BaseHandler
+from synapse.api.errors import SynapseError
 from synapse.types import UserID, create_requester
 from synapse.util.logcontext import run_in_background
-from synapse.api.errors import SynapseError
 
-import logging
+from ._base import BaseHandler
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/handlers/device.py b/synapse/handlers/device.py
index 11c6fb3657..2d44f15da3 100644
--- a/synapse/handlers/device.py
+++ b/synapse/handlers/device.py
@@ -12,22 +12,24 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+import logging
+
+from six import iteritems, itervalues
+
+from twisted.internet import defer
+
 from synapse.api import errors
 from synapse.api.constants import EventTypes
 from synapse.api.errors import FederationDeniedError
+from synapse.types import RoomStreamToken, get_domain_from_id
 from synapse.util import stringutils
 from synapse.util.async import Linearizer
 from synapse.util.caches.expiringcache import ExpiringCache
-from synapse.util.retryutils import NotRetryingDestination
 from synapse.util.metrics import measure_func
-from synapse.types import get_domain_from_id, RoomStreamToken
-from twisted.internet import defer
+from synapse.util.retryutils import NotRetryingDestination
+
 from ._base import BaseHandler
 
-import logging
-
-from six import itervalues, iteritems
-
 logger = logging.getLogger(__name__)
 
 
@@ -537,7 +539,7 @@ class DeviceListEduUpdater(object):
                 yield self.device_handler.notify_device_update(user_id, device_ids)
             else:
                 # Simply update the single device, since we know that is the only
-                # change (becuase of the single prev_id matching the current cache)
+                # change (because of the single prev_id matching the current cache)
                 for device_id, stream_id, prev_ids, content in pending_updates:
                     yield self.store.update_remote_device_list_cache_entry(
                         user_id, device_id, content, stream_id,
diff --git a/synapse/handlers/devicemessage.py b/synapse/handlers/devicemessage.py
index f147a20b73..2e2e5261de 100644
--- a/synapse/handlers/devicemessage.py
+++ b/synapse/handlers/devicemessage.py
@@ -18,10 +18,9 @@ import logging
 from twisted.internet import defer
 
 from synapse.api.errors import SynapseError
-from synapse.types import get_domain_from_id, UserID
+from synapse.types import UserID, get_domain_from_id
 from synapse.util.stringutils import random_string
 
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/handlers/directory.py b/synapse/handlers/directory.py
index c5b6e75e03..ef866da1b6 100644
--- a/synapse/handlers/directory.py
+++ b/synapse/handlers/directory.py
@@ -14,16 +14,17 @@
 # limitations under the License.
 
 
-from twisted.internet import defer
-from ._base import BaseHandler
-
-from synapse.api.errors import SynapseError, Codes, CodeMessageException, AuthError
-from synapse.api.constants import EventTypes
-from synapse.types import RoomAlias, UserID, get_domain_from_id
-
 import logging
 import string
 
+from twisted.internet import defer
+
+from synapse.api.constants import EventTypes
+from synapse.api.errors import AuthError, CodeMessageException, Codes, SynapseError
+from synapse.types import RoomAlias, UserID, get_domain_from_id
+
+from ._base import BaseHandler
+
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/handlers/e2e_keys.py b/synapse/handlers/e2e_keys.py
index 62b4892a4e..5816bf8b4f 100644
--- a/synapse/handlers/e2e_keys.py
+++ b/synapse/handlers/e2e_keys.py
@@ -16,14 +16,14 @@
 
 import logging
 
-from canonicaljson import encode_canonical_json, json
-from twisted.internet import defer
 from six import iteritems
 
-from synapse.api.errors import (
-    SynapseError, CodeMessageException, FederationDeniedError,
-)
-from synapse.types import get_domain_from_id, UserID
+from canonicaljson import encode_canonical_json, json
+
+from twisted.internet import defer
+
+from synapse.api.errors import CodeMessageException, FederationDeniedError, SynapseError
+from synapse.types import UserID, get_domain_from_id
 from synapse.util.logcontext import make_deferred_yieldable, run_in_background
 from synapse.util.retryutils import NotRetryingDestination
 
diff --git a/synapse/handlers/events.py b/synapse/handlers/events.py
index 8bc642675f..c3f2d7feff 100644
--- a/synapse/handlers/events.py
+++ b/synapse/handlers/events.py
@@ -13,19 +13,18 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer
-
-from synapse.util.logutils import log_function
-from synapse.types import UserID
-from synapse.events.utils import serialize_event
-from synapse.api.constants import Membership, EventTypes
-from synapse.events import EventBase
-
-from ._base import BaseHandler
-
 import logging
 import random
 
+from twisted.internet import defer
+
+from synapse.api.constants import EventTypes, Membership
+from synapse.events import EventBase
+from synapse.events.utils import serialize_event
+from synapse.types import UserID
+from synapse.util.logutils import log_function
+
+from ._base import BaseHandler
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/handlers/federation.py b/synapse/handlers/federation.py
index 13117d70fe..d3ecebd29f 100644
--- a/synapse/handlers/federation.py
+++ b/synapse/handlers/federation.py
@@ -20,38 +20,42 @@ import itertools
 import logging
 import sys
 
+import six
+from six import iteritems
+from six.moves import http_client
+
 from signedjson.key import decode_verify_key_bytes
 from signedjson.sign import verify_signed_json
-import six
-from six.moves import http_client
-from six import iteritems
-from twisted.internet import defer
 from unpaddedbase64 import decode_base64
 
-from ._base import BaseHandler
+from twisted.internet import defer
 
-from synapse.api.errors import (
-    AuthError, FederationError, StoreError, CodeMessageException, SynapseError,
-    FederationDeniedError,
-)
 from synapse.api.constants import EventTypes, Membership, RejectedReason
-from synapse.events.validator import EventValidator
-from synapse.util import unwrapFirstError, logcontext
-from synapse.util.metrics import measure_func
-from synapse.util.logutils import log_function
-from synapse.util.async import Linearizer
-from synapse.util.frozenutils import unfreeze
-from synapse.crypto.event_signing import (
-    compute_event_signature, add_hashes_and_signatures,
+from synapse.api.errors import (
+    AuthError,
+    CodeMessageException,
+    FederationDeniedError,
+    FederationError,
+    StoreError,
+    SynapseError,
 )
+from synapse.crypto.event_signing import (
+    add_hashes_and_signatures,
+    compute_event_signature,
+)
+from synapse.events.utils import prune_event
+from synapse.events.validator import EventValidator
 from synapse.state import resolve_events_with_factory
 from synapse.types import UserID, get_domain_from_id
-
-from synapse.events.utils import prune_event
-
+from synapse.util import logcontext, unwrapFirstError
+from synapse.util.async import Linearizer
+from synapse.util.distributor import user_joined_room
+from synapse.util.frozenutils import unfreeze
+from synapse.util.logutils import log_function
+from synapse.util.metrics import measure_func
 from synapse.util.retryutils import NotRetryingDestination
 
-from synapse.util.distributor import user_joined_room
+from ._base import BaseHandler
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/handlers/groups_local.py b/synapse/handlers/groups_local.py
index dcae083734..53e5e2648b 100644
--- a/synapse/handlers/groups_local.py
+++ b/synapse/handlers/groups_local.py
@@ -14,14 +14,15 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer
+import logging
+
 from six import iteritems
 
+from twisted.internet import defer
+
 from synapse.api.errors import SynapseError
 from synapse.types import get_domain_from_id
 
-import logging
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/handlers/identity.py b/synapse/handlers/identity.py
index 277c2b7760..8c8aedb2b8 100644
--- a/synapse/handlers/identity.py
+++ b/synapse/handlers/identity.py
@@ -24,10 +24,13 @@ from canonicaljson import json
 from twisted.internet import defer
 
 from synapse.api.errors import (
-    MatrixCodeMessageException, CodeMessageException
+    CodeMessageException,
+    Codes,
+    MatrixCodeMessageException,
+    SynapseError,
 )
+
 from ._base import BaseHandler
-from synapse.api.errors import SynapseError, Codes
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/handlers/initial_sync.py b/synapse/handlers/initial_sync.py
index 5242309c1e..64d4245f16 100644
--- a/synapse/handlers/initial_sync.py
+++ b/synapse/handlers/initial_sync.py
@@ -13,6 +13,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import logging
+
 from twisted.internet import defer
 
 from synapse.api.constants import EventTypes, Membership
@@ -21,9 +23,7 @@ from synapse.events.utils import serialize_event
 from synapse.events.validator import EventValidator
 from synapse.handlers.presence import format_user_presence_state
 from synapse.streams.config import PaginationConfig
-from synapse.types import (
-    UserID, StreamToken,
-)
+from synapse.types import StreamToken, UserID
 from synapse.util import unwrapFirstError
 from synapse.util.async import concurrently_execute
 from synapse.util.caches.snapshot_cache import SnapshotCache
@@ -32,9 +32,6 @@ from synapse.visibility import filter_events_for_client
 
 from ._base import BaseHandler
 
-import logging
-
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/handlers/message.py b/synapse/handlers/message.py
index 1ee2d32ca7..01a8f5501c 100644
--- a/synapse/handlers/message.py
+++ b/synapse/handlers/message.py
@@ -16,32 +16,29 @@
 import logging
 import sys
 
-from canonicaljson import encode_canonical_json, json
 import six
-from six import string_types, itervalues, iteritems
+from six import iteritems, itervalues, string_types
+
+from canonicaljson import encode_canonical_json, json
+
 from twisted.internet import defer
 from twisted.internet.defer import succeed
 from twisted.python.failure import Failure
 
-from synapse.api.constants import EventTypes, Membership, MAX_DEPTH
-from synapse.api.errors import (
-    AuthError, Codes, SynapseError,
-    ConsentNotGivenError,
-)
+from synapse.api.constants import MAX_DEPTH, EventTypes, Membership
+from synapse.api.errors import AuthError, Codes, ConsentNotGivenError, SynapseError
 from synapse.api.urls import ConsentURIBuilder
 from synapse.crypto.event_signing import add_hashes_and_signatures
 from synapse.events.utils import serialize_event
 from synapse.events.validator import EventValidator
-from synapse.types import (
-    UserID, RoomAlias, RoomStreamToken,
-)
-from synapse.util.async import ReadWriteLock, Limiter
+from synapse.replication.http.send_event import send_event_to_master
+from synapse.types import RoomAlias, RoomStreamToken, UserID
+from synapse.util.async import Limiter, ReadWriteLock
+from synapse.util.frozenutils import frozendict_json_encoder
 from synapse.util.logcontext import run_in_background
 from synapse.util.metrics import measure_func
-from synapse.util.frozenutils import frozendict_json_encoder
 from synapse.util.stringutils import random_string
 from synapse.visibility import filter_events_for_client
-from synapse.replication.http.send_event import send_event_to_master
 
 from ._base import BaseHandler
 
@@ -387,7 +384,7 @@ class MessageHandler(BaseHandler):
         users_with_profile = yield self.state.get_current_user_in_room(room_id)
 
         # If this is an AS, double check that they are allowed to see the members.
-        # This can either be because the AS user is in the room or becuase there
+        # This can either be because the AS user is in the room or because there
         # is a user in the room that the AS is "interested in"
         if False and requester.app_service and user_id not in users_with_profile:
             for uid in users_with_profile:
diff --git a/synapse/handlers/presence.py b/synapse/handlers/presence.py
index cc4d0fa5c2..d030cfe77c 100644
--- a/synapse/handlers/presence.py
+++ b/synapse/handlers/presence.py
@@ -22,27 +22,26 @@ The methods that define policy are:
     - should_notify
 """
 
-from twisted.internet import defer
+import logging
 from contextlib import contextmanager
 
-from six import itervalues, iteritems
+from six import iteritems, itervalues
+
+from prometheus_client import Counter
+
+from twisted.internet import defer
 
-from synapse.api.errors import SynapseError
 from synapse.api.constants import PresenceState
+from synapse.api.errors import SynapseError
+from synapse.metrics import LaterGauge
 from synapse.storage.presence import UserPresenceState
-
-from synapse.util.caches.descriptors import cachedInlineCallbacks
+from synapse.types import UserID, get_domain_from_id
 from synapse.util.async import Linearizer
+from synapse.util.caches.descriptors import cachedInlineCallbacks
 from synapse.util.logcontext import run_in_background
 from synapse.util.logutils import log_function
 from synapse.util.metrics import Measure
 from synapse.util.wheel_timer import WheelTimer
-from synapse.types import UserID, get_domain_from_id
-from synapse.metrics import LaterGauge
-
-import logging
-
-from prometheus_client import Counter
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/handlers/profile.py b/synapse/handlers/profile.py
index 3465a787ab..859f6d2b2e 100644
--- a/synapse/handlers/profile.py
+++ b/synapse/handlers/profile.py
@@ -17,8 +17,9 @@ import logging
 
 from twisted.internet import defer
 
-from synapse.api.errors import SynapseError, AuthError, CodeMessageException
+from synapse.api.errors import AuthError, CodeMessageException, SynapseError
 from synapse.types import UserID, get_domain_from_id
+
 from ._base import BaseHandler
 
 logger = logging.getLogger(__name__)
diff --git a/synapse/handlers/read_marker.py b/synapse/handlers/read_marker.py
index 5142ae153d..995460f82a 100644
--- a/synapse/handlers/read_marker.py
+++ b/synapse/handlers/read_marker.py
@@ -13,13 +13,14 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import BaseHandler
+import logging
 
 from twisted.internet import defer
 
 from synapse.util.async import Linearizer
 
-import logging
+from ._base import BaseHandler
+
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/handlers/receipts.py b/synapse/handlers/receipts.py
index 2e0672161c..cb905a3903 100644
--- a/synapse/handlers/receipts.py
+++ b/synapse/handlers/receipts.py
@@ -12,17 +12,15 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-from synapse.util import logcontext
-
-from ._base import BaseHandler
+import logging
 
 from twisted.internet import defer
 
-from synapse.util.logcontext import PreserveLoggingContext
 from synapse.types import get_domain_from_id
+from synapse.util import logcontext
+from synapse.util.logcontext import PreserveLoggingContext
 
-import logging
-
+from ._base import BaseHandler
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/handlers/register.py b/synapse/handlers/register.py
index e76ef5426d..7caff0cbc8 100644
--- a/synapse/handlers/register.py
+++ b/synapse/handlers/register.py
@@ -18,14 +18,19 @@ import logging
 
 from twisted.internet import defer
 
+from synapse import types
 from synapse.api.errors import (
-    AuthError, Codes, SynapseError, RegistrationError, InvalidCaptchaError
+    AuthError,
+    Codes,
+    InvalidCaptchaError,
+    RegistrationError,
+    SynapseError,
 )
 from synapse.http.client import CaptchaServerHttpClient
-from synapse import types
-from synapse.types import UserID, create_requester, RoomID, RoomAlias
+from synapse.types import RoomAlias, RoomID, UserID, create_requester
 from synapse.util.async import Linearizer
 from synapse.util.threepids import check_3pid_allowed
+
 from ._base import BaseHandler
 
 logger = logging.getLogger(__name__)
diff --git a/synapse/handlers/room.py b/synapse/handlers/room.py
index ab72963d87..f67512078b 100644
--- a/synapse/handlers/room.py
+++ b/synapse/handlers/room.py
@@ -15,23 +15,20 @@
 # limitations under the License.
 
 """Contains functions for performing events on rooms."""
-from twisted.internet import defer
-
-from ._base import BaseHandler
-
-from synapse.types import UserID, RoomAlias, RoomID, RoomStreamToken
-from synapse.api.constants import (
-    EventTypes, JoinRules, RoomCreationPreset
-)
-from synapse.api.errors import AuthError, Codes, StoreError, SynapseError
-from synapse.util import stringutils
-from synapse.visibility import filter_events_for_client
-
-from collections import OrderedDict
-
 import logging
 import math
 import string
+from collections import OrderedDict
+
+from twisted.internet import defer
+
+from synapse.api.constants import EventTypes, JoinRules, RoomCreationPreset
+from synapse.api.errors import AuthError, Codes, StoreError, SynapseError
+from synapse.types import RoomAlias, RoomID, RoomStreamToken, UserID
+from synapse.util import stringutils
+from synapse.visibility import filter_events_for_client
+
+from ._base import BaseHandler
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/handlers/room_list.py b/synapse/handlers/room_list.py
index 878db0db1e..eaae393afb 100644
--- a/synapse/handlers/room_list.py
+++ b/synapse/handlers/room_list.py
@@ -13,26 +13,24 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer
+import logging
+from collections import namedtuple
 
 from six import iteritems
 from six.moves import range
 
-from ._base import BaseHandler
+import msgpack
+from unpaddedbase64 import decode_base64, encode_base64
 
-from synapse.api.constants import (
-    EventTypes, JoinRules,
-)
+from twisted.internet import defer
+
+from synapse.api.constants import EventTypes, JoinRules
+from synapse.types import ThirdPartyInstanceID
 from synapse.util.async import concurrently_execute
 from synapse.util.caches.descriptors import cachedInlineCallbacks
 from synapse.util.caches.response_cache import ResponseCache
-from synapse.types import ThirdPartyInstanceID
 
-from collections import namedtuple
-from unpaddedbase64 import encode_base64, decode_base64
-
-import logging
-import msgpack
+from ._base import BaseHandler
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/handlers/room_member.py b/synapse/handlers/room_member.py
index 7d509f9e08..05f0f7621d 100644
--- a/synapse/handlers/room_member.py
+++ b/synapse/handlers/room_member.py
@@ -21,19 +21,17 @@ from six.moves import http_client
 
 from signedjson.key import decode_verify_key_bytes
 from signedjson.sign import verify_signed_json
-from twisted.internet import defer
 from unpaddedbase64 import decode_base64
 
+from twisted.internet import defer
+
 import synapse.server
 import synapse.types
-from synapse.api.constants import (
-    EventTypes, Membership,
-)
-from synapse.api.errors import AuthError, SynapseError, Codes
-from synapse.types import UserID, RoomID
-from synapse.util.async import Linearizer, Limiter
-from synapse.util.distributor import user_left_room, user_joined_room
-
+from synapse.api.constants import EventTypes, Membership
+from synapse.api.errors import AuthError, Codes, SynapseError
+from synapse.types import RoomID, UserID
+from synapse.util.async import Limiter, Linearizer
+from synapse.util.distributor import user_joined_room, user_left_room
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/handlers/room_member_worker.py b/synapse/handlers/room_member_worker.py
index 493aec1e48..22d8b4b0d3 100644
--- a/synapse/handlers/room_member_worker.py
+++ b/synapse/handlers/room_member_worker.py
@@ -20,11 +20,12 @@ from twisted.internet import defer
 from synapse.api.errors import SynapseError
 from synapse.handlers.room_member import RoomMemberHandler
 from synapse.replication.http.membership import (
-    remote_join, remote_reject_invite, get_or_register_3pid_guest,
+    get_or_register_3pid_guest,
     notify_user_membership_change,
+    remote_join,
+    remote_reject_invite,
 )
 
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/handlers/search.py b/synapse/handlers/search.py
index 2e3a77ca4b..69ae9731d5 100644
--- a/synapse/handlers/search.py
+++ b/synapse/handlers/search.py
@@ -13,21 +13,20 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer
-
-from ._base import BaseHandler
-
-from synapse.api.constants import Membership, EventTypes
-from synapse.api.filtering import Filter
-from synapse.api.errors import SynapseError
-from synapse.events.utils import serialize_event
-from synapse.visibility import filter_events_for_client
-
-from unpaddedbase64 import decode_base64, encode_base64
-
 import itertools
 import logging
 
+from unpaddedbase64 import decode_base64, encode_base64
+
+from twisted.internet import defer
+
+from synapse.api.constants import EventTypes, Membership
+from synapse.api.errors import SynapseError
+from synapse.api.filtering import Filter
+from synapse.events.utils import serialize_event
+from synapse.visibility import filter_events_for_client
+
+from ._base import BaseHandler
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/handlers/set_password.py b/synapse/handlers/set_password.py
index e057ae54c9..7ecdede4dc 100644
--- a/synapse/handlers/set_password.py
+++ b/synapse/handlers/set_password.py
@@ -17,6 +17,7 @@ import logging
 from twisted.internet import defer
 
 from synapse.api.errors import Codes, StoreError, SynapseError
+
 from ._base import BaseHandler
 
 logger = logging.getLogger(__name__)
diff --git a/synapse/handlers/sync.py b/synapse/handlers/sync.py
index dc2446bbed..a006c952f2 100644
--- a/synapse/handlers/sync.py
+++ b/synapse/handlers/sync.py
@@ -13,22 +13,22 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.api.constants import Membership, EventTypes
-from synapse.util.async import concurrently_execute
-from synapse.util.logcontext import LoggingContext
-from synapse.util.metrics import Measure, measure_func
-from synapse.util.caches.response_cache import ResponseCache
-from synapse.push.clientformat import format_push_rules_for_user
-from synapse.visibility import filter_events_for_client
-from synapse.types import RoomStreamToken
+import collections
+import itertools
+import logging
+
+from six import iteritems, itervalues
 
 from twisted.internet import defer
 
-import collections
-import logging
-import itertools
-
-from six import itervalues, iteritems
+from synapse.api.constants import EventTypes, Membership
+from synapse.push.clientformat import format_push_rules_for_user
+from synapse.types import RoomStreamToken
+from synapse.util.async import concurrently_execute
+from synapse.util.caches.response_cache import ResponseCache
+from synapse.util.logcontext import LoggingContext
+from synapse.util.metrics import Measure, measure_func
+from synapse.visibility import filter_events_for_client
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/handlers/typing.py b/synapse/handlers/typing.py
index 5d9736e88f..2d2d3d5a0d 100644
--- a/synapse/handlers/typing.py
+++ b/synapse/handlers/typing.py
@@ -13,17 +13,16 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import logging
+from collections import namedtuple
+
 from twisted.internet import defer
 
-from synapse.api.errors import SynapseError, AuthError
+from synapse.api.errors import AuthError, SynapseError
+from synapse.types import UserID, get_domain_from_id
 from synapse.util.logcontext import run_in_background
 from synapse.util.metrics import Measure
 from synapse.util.wheel_timer import WheelTimer
-from synapse.types import UserID, get_domain_from_id
-
-import logging
-
-from collections import namedtuple
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/handlers/user_directory.py b/synapse/handlers/user_directory.py
index 7e4a114d4f..37dda64587 100644
--- a/synapse/handlers/user_directory.py
+++ b/synapse/handlers/user_directory.py
@@ -14,14 +14,15 @@
 # limitations under the License.
 
 import logging
+
+from six import iteritems
+
 from twisted.internet import defer
 
 from synapse.api.constants import EventTypes, JoinRules, Membership
 from synapse.storage.roommember import ProfileInfo
-from synapse.util.metrics import Measure
 from synapse.types import get_localpart_from_id
-
-from six import iteritems
+from synapse.util.metrics import Measure
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/http/additional_resource.py b/synapse/http/additional_resource.py
index a797396ade..0e10e3f8f7 100644
--- a/synapse/http/additional_resource.py
+++ b/synapse/http/additional_resource.py
@@ -13,10 +13,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.http.server import wrap_json_request_handler
 from twisted.web.resource import Resource
 from twisted.web.server import NOT_DONE_YET
 
+from synapse.http.server import wrap_json_request_handler
+
 
 class AdditionalResource(Resource):
     """Resource wrapper for additional_resources
diff --git a/synapse/http/client.py b/synapse/http/client.py
index 5bdc484c15..d6a0d75b2b 100644
--- a/synapse/http/client.py
+++ b/synapse/http/client.py
@@ -13,39 +13,41 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-from OpenSSL import SSL
-from OpenSSL.SSL import VERIFY_NONE
-
-from synapse.api.errors import (
-    CodeMessageException, MatrixCodeMessageException, SynapseError, Codes,
-)
-from synapse.http import cancelled_to_request_timed_out_error, redact_uri
-from synapse.util.async import add_timeout_to_deferred
-from synapse.util.caches import CACHE_SIZE_FACTOR
-from synapse.util.logcontext import make_deferred_yieldable
-from synapse.http.endpoint import SpiderEndpoint
-
-from canonicaljson import encode_canonical_json
-
-from twisted.internet import defer, reactor, ssl, protocol, task
-from twisted.internet.endpoints import HostnameEndpoint, wrapClientTLS
-from twisted.web.client import (
-    BrowserLikeRedirectAgent, ContentDecoderAgent, GzipDecoder, Agent,
-    readBody, PartialDownloadError,
-    HTTPConnectionPool,
-)
-from twisted.web.client import FileBodyProducer as TwistedFileBodyProducer
-from twisted.web.http import PotentialDataLoss
-from twisted.web.http_headers import Headers
-from twisted.web._newclient import ResponseDone
-
-from six import StringIO
-
-from prometheus_client import Counter
-from canonicaljson import json
 import logging
 import urllib
 
+from six import StringIO
+
+from canonicaljson import encode_canonical_json, json
+from prometheus_client import Counter
+
+from OpenSSL import SSL
+from OpenSSL.SSL import VERIFY_NONE
+from twisted.internet import defer, protocol, reactor, ssl, task
+from twisted.internet.endpoints import HostnameEndpoint, wrapClientTLS
+from twisted.web._newclient import ResponseDone
+from twisted.web.client import Agent, BrowserLikeRedirectAgent, ContentDecoderAgent
+from twisted.web.client import FileBodyProducer as TwistedFileBodyProducer
+from twisted.web.client import (
+    GzipDecoder,
+    HTTPConnectionPool,
+    PartialDownloadError,
+    readBody,
+)
+from twisted.web.http import PotentialDataLoss
+from twisted.web.http_headers import Headers
+
+from synapse.api.errors import (
+    CodeMessageException,
+    Codes,
+    MatrixCodeMessageException,
+    SynapseError,
+)
+from synapse.http import cancelled_to_request_timed_out_error, redact_uri
+from synapse.http.endpoint import SpiderEndpoint
+from synapse.util.async import add_timeout_to_deferred
+from synapse.util.caches import CACHE_SIZE_FACTOR
+from synapse.util.logcontext import make_deferred_yieldable
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/http/endpoint.py b/synapse/http/endpoint.py
index 1b1123b292..d65daa72bb 100644
--- a/synapse/http/endpoint.py
+++ b/synapse/http/endpoint.py
@@ -12,19 +12,17 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-import re
-
-from twisted.internet.endpoints import HostnameEndpoint, wrapClientTLS
-from twisted.internet import defer
-from twisted.internet.error import ConnectError
-from twisted.names import client, dns
-from twisted.names.error import DNSNameError, DomainError
-
 import collections
 import logging
 import random
+import re
 import time
 
+from twisted.internet import defer
+from twisted.internet.endpoints import HostnameEndpoint, wrapClientTLS
+from twisted.internet.error import ConnectError
+from twisted.names import client, dns
+from twisted.names.error import DNSNameError, DomainError
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/http/matrixfederationclient.py b/synapse/http/matrixfederationclient.py
index 2cb9e3e231..bf1aa29502 100644
--- a/synapse/http/matrixfederationclient.py
+++ b/synapse/http/matrixfederationclient.py
@@ -13,38 +13,38 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-from twisted.internet import defer, reactor, protocol
-from twisted.internet.error import DNSLookupError
-from twisted.web.client import readBody, HTTPConnectionPool, Agent
-from twisted.web.http_headers import Headers
-from twisted.web._newclient import ResponseDone
-
-from synapse.http import cancelled_to_request_timed_out_error
-from synapse.http.endpoint import matrix_federation_endpoint
-import synapse.metrics
-from synapse.util.async import add_timeout_to_deferred
-from synapse.util import logcontext
-from synapse.util.logcontext import make_deferred_yieldable
-import synapse.util.retryutils
-
-from canonicaljson import encode_canonical_json, json
-
-from synapse.api.errors import (
-    SynapseError, Codes, HttpResponseException, FederationDeniedError,
-)
-
-from signedjson.sign import sign_json
-
 import cgi
 import logging
 import random
 import sys
 import urllib
-from six.moves.urllib import parse as urlparse
+
 from six import string_types
+from six.moves.urllib import parse as urlparse
 
-
+from canonicaljson import encode_canonical_json, json
 from prometheus_client import Counter
+from signedjson.sign import sign_json
+
+from twisted.internet import defer, protocol, reactor
+from twisted.internet.error import DNSLookupError
+from twisted.web._newclient import ResponseDone
+from twisted.web.client import Agent, HTTPConnectionPool, readBody
+from twisted.web.http_headers import Headers
+
+import synapse.metrics
+import synapse.util.retryutils
+from synapse.api.errors import (
+    Codes,
+    FederationDeniedError,
+    HttpResponseException,
+    SynapseError,
+)
+from synapse.http import cancelled_to_request_timed_out_error
+from synapse.http.endpoint import matrix_federation_endpoint
+from synapse.util import logcontext
+from synapse.util.async import add_timeout_to_deferred
+from synapse.util.logcontext import make_deferred_yieldable
 
 logger = logging.getLogger(__name__)
 outbound_logger = logging.getLogger("synapse.http.outbound")
diff --git a/synapse/http/request_metrics.py b/synapse/http/request_metrics.py
index 1b711ca2de..f24b4b949c 100644
--- a/synapse/http/request_metrics.py
+++ b/synapse/http/request_metrics.py
@@ -17,8 +17,8 @@
 import logging
 
 from prometheus_client.core import Counter, Histogram
-from synapse.metrics import LaterGauge
 
+from synapse.metrics import LaterGauge
 from synapse.util.logcontext import LoggingContext
 
 logger = logging.getLogger(__name__)
@@ -149,7 +149,9 @@ class RequestMetrics(object):
         self.name = name
         self.method = method
 
-        self._request_stats = _RequestStats.from_context(self.start_context)
+        # _request_stats records resource usage that we have already added
+        # to the "in flight" metrics.
+        self._request_stats = self.start_context.get_resource_usage()
 
         _in_flight_requests.add(self)
 
@@ -177,18 +179,22 @@ class RequestMetrics(object):
             time_sec - self.start
         )
 
-        ru_utime, ru_stime = context.get_resource_usage()
+        resource_usage = context.get_resource_usage()
 
-        response_ru_utime.labels(request.method, self.name, tag).inc(ru_utime)
-        response_ru_stime.labels(request.method, self.name, tag).inc(ru_stime)
+        response_ru_utime.labels(request.method, self.name, tag).inc(
+            resource_usage.ru_utime,
+        )
+        response_ru_stime.labels(request.method, self.name, tag).inc(
+            resource_usage.ru_stime,
+        )
         response_db_txn_count.labels(request.method, self.name, tag).inc(
-            context.db_txn_count
+            resource_usage.db_txn_count
         )
         response_db_txn_duration.labels(request.method, self.name, tag).inc(
-            context.db_txn_duration_sec
+            resource_usage.db_txn_duration_sec
         )
         response_db_sched_duration.labels(request.method, self.name, tag).inc(
-            context.db_sched_duration_sec
+            resource_usage.db_sched_duration_sec
         )
 
         response_size.labels(request.method, self.name, tag).inc(request.sentLength)
@@ -201,7 +207,10 @@ class RequestMetrics(object):
     def update_metrics(self):
         """Updates the in flight metrics with values from this request.
         """
-        diff = self._request_stats.update(self.start_context)
+        new_stats = self.start_context.get_resource_usage()
+
+        diff = new_stats - self._request_stats
+        self._request_stats = new_stats
 
         in_flight_requests_ru_utime.labels(self.method, self.name).inc(diff.ru_utime)
         in_flight_requests_ru_stime.labels(self.method, self.name).inc(diff.ru_stime)
@@ -217,61 +226,3 @@ class RequestMetrics(object):
         in_flight_requests_db_sched_duration.labels(self.method, self.name).inc(
             diff.db_sched_duration_sec
         )
-
-
-class _RequestStats(object):
-    """Keeps tracks of various metrics for an in flight request.
-    """
-
-    __slots__ = [
-        "ru_utime",
-        "ru_stime",
-        "db_txn_count",
-        "db_txn_duration_sec",
-        "db_sched_duration_sec",
-    ]
-
-    def __init__(
-        self, ru_utime, ru_stime, db_txn_count, db_txn_duration_sec, db_sched_duration_sec
-    ):
-        self.ru_utime = ru_utime
-        self.ru_stime = ru_stime
-        self.db_txn_count = db_txn_count
-        self.db_txn_duration_sec = db_txn_duration_sec
-        self.db_sched_duration_sec = db_sched_duration_sec
-
-    @staticmethod
-    def from_context(context):
-        ru_utime, ru_stime = context.get_resource_usage()
-
-        return _RequestStats(
-            ru_utime, ru_stime,
-            context.db_txn_count,
-            context.db_txn_duration_sec,
-            context.db_sched_duration_sec,
-        )
-
-    def update(self, context):
-        """Updates the current values and returns the difference between the
-        old and new values.
-
-        Returns:
-            _RequestStats: The difference between the old and new values
-        """
-        new = _RequestStats.from_context(context)
-
-        diff = _RequestStats(
-            new.ru_utime - self.ru_utime,
-            new.ru_stime - self.ru_stime,
-            new.db_txn_count - self.db_txn_count,
-            new.db_txn_duration_sec - self.db_txn_duration_sec,
-            new.db_sched_duration_sec - self.db_sched_duration_sec,
-        )
-
-        self.ru_utime = new.ru_utime
-        self.ru_stime = new.ru_stime
-        self.db_txn_count = new.db_txn_count
-        self.db_txn_duration_sec = new.db_txn_duration_sec
-        self.db_sched_duration_sec = new.db_sched_duration_sec
-
-        return diff
diff --git a/synapse/http/server.py b/synapse/http/server.py
index 517aaf7b5a..c70fdbdfd2 100644
--- a/synapse/http/server.py
+++ b/synapse/http/server.py
@@ -14,34 +14,34 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import cgi
-from six.moves import http_client
-
-from synapse.api.errors import (
-    cs_exception, SynapseError, CodeMessageException, UnrecognizedRequestError, Codes
-)
-from synapse.http.request_metrics import (
-    requests_counter,
-)
-from synapse.util.logcontext import LoggingContext, PreserveLoggingContext
-from synapse.util.caches import intern_dict
-from synapse.util.metrics import Measure
-import synapse.metrics
-import synapse.events
-
-from canonicaljson import (
-    encode_canonical_json, encode_pretty_printed_json, json
-)
-
-from twisted.internet import defer
-from twisted.python import failure
-from twisted.web import server, resource
-from twisted.web.server import NOT_DONE_YET
-from twisted.web.util import redirectTo
-
 import collections
 import logging
 import urllib
 
+from six.moves import http_client
+
+from canonicaljson import encode_canonical_json, encode_pretty_printed_json, json
+
+from twisted.internet import defer
+from twisted.python import failure
+from twisted.web import resource, server
+from twisted.web.server import NOT_DONE_YET
+from twisted.web.util import redirectTo
+
+import synapse.events
+import synapse.metrics
+from synapse.api.errors import (
+    CodeMessageException,
+    Codes,
+    SynapseError,
+    UnrecognizedRequestError,
+    cs_exception,
+)
+from synapse.http.request_metrics import requests_counter
+from synapse.util.caches import intern_dict
+from synapse.util.logcontext import LoggingContext, PreserveLoggingContext
+from synapse.util.metrics import Measure
+
 logger = logging.getLogger(__name__)
 
 HTML_ERROR_TEMPLATE = """<!DOCTYPE html>
diff --git a/synapse/http/servlet.py b/synapse/http/servlet.py
index ef3a01ddc7..cf6723563a 100644
--- a/synapse/http/servlet.py
+++ b/synapse/http/servlet.py
@@ -15,12 +15,11 @@
 
 """ This module contains base REST classes for constructing REST servlets. """
 
-from synapse.api.errors import SynapseError, Codes
-
 import logging
 
 from canonicaljson import json
 
+from synapse.api.errors import Codes, SynapseError
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/http/site.py b/synapse/http/site.py
index fe93643b1e..21e26f9c5e 100644
--- a/synapse/http/site.py
+++ b/synapse/http/site.py
@@ -16,11 +16,11 @@ import contextlib
 import logging
 import time
 
-from twisted.web.server import Site, Request
+from twisted.web.server import Request, Site
 
 from synapse.http import redact_uri
 from synapse.http.request_metrics import RequestMetrics
-from synapse.util.logcontext import LoggingContext
+from synapse.util.logcontext import LoggingContext, ContextResourceUsage
 
 logger = logging.getLogger(__name__)
 
@@ -95,15 +95,9 @@ class SynapseRequest(Request):
     def _finished_processing(self):
         try:
             context = LoggingContext.current_context()
-            ru_utime, ru_stime = context.get_resource_usage()
-            db_txn_count = context.db_txn_count
-            db_txn_duration_sec = context.db_txn_duration_sec
-            db_sched_duration_sec = context.db_sched_duration_sec
-            evt_db_fetch_count = context.evt_db_fetch_count
+            usage = context.get_resource_usage()
         except Exception:
-            ru_utime, ru_stime = (0, 0)
-            db_txn_count, db_txn_duration_sec = (0, 0)
-            evt_db_fetch_count = 0
+            usage = ContextResourceUsage()
 
         end_time = time.time()
 
@@ -130,18 +124,18 @@ class SynapseRequest(Request):
             self.site.site_tag,
             authenticated_entity,
             end_time - self.start_time,
-            ru_utime,
-            ru_stime,
-            db_sched_duration_sec,
-            db_txn_duration_sec,
-            int(db_txn_count),
+            usage.ru_utime,
+            usage.ru_stime,
+            usage.db_sched_duration_sec,
+            usage.db_txn_duration_sec,
+            int(usage.db_txn_count),
             self.sentLength,
             self.code,
             self.method,
             self.get_redacted_uri(),
             self.clientproto,
             user_agent,
-            evt_db_fetch_count,
+            usage.evt_db_fetch_count,
         )
 
         try:
diff --git a/synapse/metrics/__init__.py b/synapse/metrics/__init__.py
index 2d2397caae..a9158fc066 100644
--- a/synapse/metrics/__init__.py
+++ b/synapse/metrics/__init__.py
@@ -13,20 +13,19 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import logging
 import functools
-import time
 import gc
+import logging
 import os
 import platform
-import attr
+import time
 
-from prometheus_client import Gauge, Histogram, Counter
-from prometheus_client.core import GaugeMetricFamily, REGISTRY
+import attr
+from prometheus_client import Counter, Gauge, Histogram
+from prometheus_client.core import REGISTRY, GaugeMetricFamily
 
 from twisted.internet import reactor
 
-
 logger = logging.getLogger(__name__)
 
 running_on_pypy = platform.python_implementation() == "PyPy"
diff --git a/synapse/notifier.py b/synapse/notifier.py
index 3c0622a294..51cbd66f06 100644
--- a/synapse/notifier.py
+++ b/synapse/notifier.py
@@ -13,28 +13,27 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import logging
+from collections import namedtuple
+
+from prometheus_client import Counter
+
 from twisted.internet import defer
 
 from synapse.api.constants import EventTypes, Membership
 from synapse.api.errors import AuthError
 from synapse.handlers.presence import format_user_presence_state
-
-from synapse.util.logutils import log_function
+from synapse.metrics import LaterGauge
+from synapse.types import StreamToken
 from synapse.util.async import (
-    ObservableDeferred, add_timeout_to_deferred,
     DeferredTimeoutError,
+    ObservableDeferred,
+    add_timeout_to_deferred,
 )
 from synapse.util.logcontext import PreserveLoggingContext, run_in_background
+from synapse.util.logutils import log_function
 from synapse.util.metrics import Measure
-from synapse.types import StreamToken
 from synapse.visibility import filter_events_for_client
-from synapse.metrics import LaterGauge
-
-from collections import namedtuple
-from prometheus_client import Counter
-
-import logging
-
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/push/action_generator.py b/synapse/push/action_generator.py
index 8f619a7a1b..a5de75c48a 100644
--- a/synapse/push/action_generator.py
+++ b/synapse/push/action_generator.py
@@ -13,13 +13,13 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer
+import logging
 
-from .bulk_push_rule_evaluator import BulkPushRuleEvaluator
+from twisted.internet import defer
 
 from synapse.util.metrics import Measure
 
-import logging
+from .bulk_push_rule_evaluator import BulkPushRuleEvaluator
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/push/baserules.py b/synapse/push/baserules.py
index a8ae7bcd6c..8f0682c948 100644
--- a/synapse/push/baserules.py
+++ b/synapse/push/baserules.py
@@ -13,9 +13,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.push.rulekinds import PRIORITY_CLASS_MAP, PRIORITY_CLASS_INVERSE_MAP
 import copy
 
+from synapse.push.rulekinds import PRIORITY_CLASS_INVERSE_MAP, PRIORITY_CLASS_MAP
+
 
 def list_with_base_rules(rawrules):
     """Combine the list of rules set by the user with the default push rules
diff --git a/synapse/push/bulk_push_rule_evaluator.py b/synapse/push/bulk_push_rule_evaluator.py
index a5cab1f043..bb181d94ee 100644
--- a/synapse/push/bulk_push_rule_evaluator.py
+++ b/synapse/push/bulk_push_rule_evaluator.py
@@ -15,21 +15,22 @@
 # limitations under the License.
 
 import logging
+from collections import namedtuple
+
+from six import iteritems, itervalues
+
+from prometheus_client import Counter
 
 from twisted.internet import defer
 
-from .push_rule_evaluator import PushRuleEvaluatorForEvent
-
-from synapse.event_auth import get_user_power_level
 from synapse.api.constants import EventTypes, Membership
+from synapse.event_auth import get_user_power_level
+from synapse.state import POWER_KEY
+from synapse.util.async import Linearizer
 from synapse.util.caches import register_cache
 from synapse.util.caches.descriptors import cached
-from synapse.util.async import Linearizer
-from synapse.state import POWER_KEY
 
-from collections import namedtuple
-from prometheus_client import Counter
-from six import itervalues, iteritems
+from .push_rule_evaluator import PushRuleEvaluatorForEvent
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/push/clientformat.py b/synapse/push/clientformat.py
index e0331b2d2d..ecbf364a5e 100644
--- a/synapse/push/clientformat.py
+++ b/synapse/push/clientformat.py
@@ -13,12 +13,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.push.rulekinds import (
-    PRIORITY_CLASS_MAP, PRIORITY_CLASS_INVERSE_MAP
-)
-
 import copy
 
+from synapse.push.rulekinds import PRIORITY_CLASS_INVERSE_MAP, PRIORITY_CLASS_MAP
+
 
 def format_push_rules_for_user(user, ruleslist):
     """Converts a list of rawrules and a enabled map into nested dictionaries
diff --git a/synapse/push/emailpusher.py b/synapse/push/emailpusher.py
index 52d4f087ee..d746371420 100644
--- a/synapse/push/emailpusher.py
+++ b/synapse/push/emailpusher.py
@@ -13,14 +13,13 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import logging
+
 from twisted.internet import defer
 from twisted.internet.error import AlreadyCalled, AlreadyCancelled
 
-import logging
-
-from synapse.util.metrics import Measure
 from synapse.util.logcontext import LoggingContext
-
+from synapse.util.metrics import Measure
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/push/httppusher.py b/synapse/push/httppusher.py
index cb63d7917f..a4e8cafdc9 100644
--- a/synapse/push/httppusher.py
+++ b/synapse/push/httppusher.py
@@ -15,16 +15,16 @@
 # limitations under the License.
 import logging
 
+from prometheus_client import Counter
+
 from twisted.internet import defer
 from twisted.internet.error import AlreadyCalled, AlreadyCancelled
 
-from . import push_rule_evaluator
-from . import push_tools
 from synapse.push import PusherConfigException
 from synapse.util.logcontext import LoggingContext
 from synapse.util.metrics import Measure
 
-from prometheus_client import Counter
+from . import push_rule_evaluator, push_tools
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/push/mailer.py b/synapse/push/mailer.py
index d4be800e5e..9d601208fd 100644
--- a/synapse/push/mailer.py
+++ b/synapse/push/mailer.py
@@ -13,30 +13,31 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import email.mime.multipart
+import email.utils
+import logging
+import time
+import urllib
+from email.mime.multipart import MIMEMultipart
+from email.mime.text import MIMEText
+
+import bleach
+import jinja2
+
 from twisted.internet import defer
 from twisted.mail.smtp import sendmail
 
-import email.utils
-import email.mime.multipart
-from email.mime.text import MIMEText
-from email.mime.multipart import MIMEMultipart
-
-from synapse.util.async import concurrently_execute
+from synapse.api.constants import EventTypes
+from synapse.api.errors import StoreError
 from synapse.push.presentable_names import (
-    calculate_room_name, name_from_member_event, descriptor_from_member_events
+    calculate_room_name,
+    descriptor_from_member_events,
+    name_from_member_event,
 )
 from synapse.types import UserID
-from synapse.api.errors import StoreError
-from synapse.api.constants import EventTypes
+from synapse.util.async import concurrently_execute
 from synapse.visibility import filter_events_for_client
 
-import jinja2
-import bleach
-
-import time
-import urllib
-
-import logging
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/push/presentable_names.py b/synapse/push/presentable_names.py
index 43f0c74ff3..eef6e18c2e 100644
--- a/synapse/push/presentable_names.py
+++ b/synapse/push/presentable_names.py
@@ -13,10 +13,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer
-
-import re
 import logging
+import re
+
+from twisted.internet import defer
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/push/push_rule_evaluator.py b/synapse/push/push_rule_evaluator.py
index cf735f7468..2bd321d530 100644
--- a/synapse/push/push_rule_evaluator.py
+++ b/synapse/push/push_rule_evaluator.py
@@ -17,12 +17,12 @@
 import logging
 import re
 
+from six import string_types
+
 from synapse.types import UserID
 from synapse.util.caches import CACHE_SIZE_FACTOR, register_cache
 from synapse.util.caches.lrucache import LruCache
 
-from six import string_types
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/push/push_tools.py b/synapse/push/push_tools.py
index 6835f54e97..8049c298c2 100644
--- a/synapse/push/push_tools.py
+++ b/synapse/push/push_tools.py
@@ -14,9 +14,8 @@
 # limitations under the License.
 
 from twisted.internet import defer
-from synapse.push.presentable_names import (
-    calculate_room_name, name_from_member_event
-)
+
+from synapse.push.presentable_names import calculate_room_name, name_from_member_event
 
 
 @defer.inlineCallbacks
diff --git a/synapse/push/pusher.py b/synapse/push/pusher.py
index 5aa6667e91..fcee6d9d7e 100644
--- a/synapse/push/pusher.py
+++ b/synapse/push/pusher.py
@@ -13,9 +13,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import logging
+
 from .httppusher import HttpPusher
 
-import logging
 logger = logging.getLogger(__name__)
 
 # We try importing this if we can (it will fail if we don't
diff --git a/synapse/python_dependencies.py b/synapse/python_dependencies.py
index 7632dd50b7..987eec3ef2 100644
--- a/synapse/python_dependencies.py
+++ b/synapse/python_dependencies.py
@@ -57,7 +57,7 @@ REQUIREMENTS = {
     "phonenumbers>=8.2.0": ["phonenumbers"],
     "six": ["six"],
     "prometheus_client": ["prometheus_client"],
-    "attr": ["attr"],
+    "attrs": ["attr"],
     "netaddr>=0.7.18": ["netaddr"],
 }
 
diff --git a/synapse/replication/http/__init__.py b/synapse/replication/http/__init__.py
index 1d7a607529..589ee94c66 100644
--- a/synapse/replication/http/__init__.py
+++ b/synapse/replication/http/__init__.py
@@ -16,7 +16,6 @@
 from synapse.http.server import JsonResource
 from synapse.replication.http import membership, send_event
 
-
 REPLICATION_PREFIX = "/_synapse/replication"
 
 
diff --git a/synapse/replication/http/membership.py b/synapse/replication/http/membership.py
index e66c4e881f..6bfc8a5b89 100644
--- a/synapse/replication/http/membership.py
+++ b/synapse/replication/http/membership.py
@@ -18,10 +18,10 @@ import re
 
 from twisted.internet import defer
 
-from synapse.api.errors import SynapseError, MatrixCodeMessageException
+from synapse.api.errors import MatrixCodeMessageException, SynapseError
 from synapse.http.servlet import RestServlet, parse_json_object_from_request
 from synapse.types import Requester, UserID
-from synapse.util.distributor import user_left_room, user_joined_room
+from synapse.util.distributor import user_joined_room, user_left_room
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/replication/http/send_event.py b/synapse/replication/http/send_event.py
index f080f96cc1..2eede54792 100644
--- a/synapse/replication/http/send_event.py
+++ b/synapse/replication/http/send_event.py
@@ -13,20 +13,22 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import logging
+import re
+
 from twisted.internet import defer
 
 from synapse.api.errors import (
-    SynapseError, MatrixCodeMessageException, CodeMessageException,
+    CodeMessageException,
+    MatrixCodeMessageException,
+    SynapseError,
 )
 from synapse.events import FrozenEvent
 from synapse.events.snapshot import EventContext
 from synapse.http.servlet import RestServlet, parse_json_object_from_request
+from synapse.types import Requester, UserID
 from synapse.util.caches.response_cache import ResponseCache
 from synapse.util.metrics import Measure
-from synapse.types import Requester, UserID
-
-import logging
-import re
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/replication/slave/storage/_base.py b/synapse/replication/slave/storage/_base.py
index 61f5590c53..3f7be74e02 100644
--- a/synapse/replication/slave/storage/_base.py
+++ b/synapse/replication/slave/storage/_base.py
@@ -13,13 +13,13 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import logging
+
 from synapse.storage._base import SQLBaseStore
 from synapse.storage.engines import PostgresEngine
 
 from ._slaved_id_tracker import SlavedIdTracker
 
-import logging
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/replication/slave/storage/appservice.py b/synapse/replication/slave/storage/appservice.py
index 8cae3076f4..b53a4c6bd1 100644
--- a/synapse/replication/slave/storage/appservice.py
+++ b/synapse/replication/slave/storage/appservice.py
@@ -15,7 +15,8 @@
 # limitations under the License.
 
 from synapse.storage.appservice import (
-    ApplicationServiceWorkerStore, ApplicationServiceTransactionWorkerStore,
+    ApplicationServiceTransactionWorkerStore,
+    ApplicationServiceWorkerStore,
 )
 
 
diff --git a/synapse/replication/slave/storage/client_ips.py b/synapse/replication/slave/storage/client_ips.py
index fedf7a3188..5b8521c770 100644
--- a/synapse/replication/slave/storage/client_ips.py
+++ b/synapse/replication/slave/storage/client_ips.py
@@ -13,11 +13,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import BaseSlavedStore
 from synapse.storage.client_ips import LAST_SEEN_GRANULARITY
 from synapse.util.caches import CACHE_SIZE_FACTOR
 from synapse.util.caches.descriptors import Cache
 
+from ._base import BaseSlavedStore
+
 
 class SlavedClientIpStore(BaseSlavedStore):
     def __init__(self, db_conn, hs):
diff --git a/synapse/replication/slave/storage/deviceinbox.py b/synapse/replication/slave/storage/deviceinbox.py
index 6f3fb64770..87eaa53004 100644
--- a/synapse/replication/slave/storage/deviceinbox.py
+++ b/synapse/replication/slave/storage/deviceinbox.py
@@ -13,11 +13,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from synapse.storage import DataStore
+from synapse.util.caches.expiringcache import ExpiringCache
+from synapse.util.caches.stream_change_cache import StreamChangeCache
+
 from ._base import BaseSlavedStore
 from ._slaved_id_tracker import SlavedIdTracker
-from synapse.storage import DataStore
-from synapse.util.caches.stream_change_cache import StreamChangeCache
-from synapse.util.caches.expiringcache import ExpiringCache
 
 
 class SlavedDeviceInboxStore(BaseSlavedStore):
diff --git a/synapse/replication/slave/storage/devices.py b/synapse/replication/slave/storage/devices.py
index 7687867aee..8206a988f7 100644
--- a/synapse/replication/slave/storage/devices.py
+++ b/synapse/replication/slave/storage/devices.py
@@ -13,12 +13,13 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import BaseSlavedStore
-from ._slaved_id_tracker import SlavedIdTracker
 from synapse.storage import DataStore
 from synapse.storage.end_to_end_keys import EndToEndKeyStore
 from synapse.util.caches.stream_change_cache import StreamChangeCache
 
+from ._base import BaseSlavedStore
+from ._slaved_id_tracker import SlavedIdTracker
+
 
 class SlavedDeviceStore(BaseSlavedStore):
     def __init__(self, db_conn, hs):
diff --git a/synapse/replication/slave/storage/directory.py b/synapse/replication/slave/storage/directory.py
index 6deecd3963..1d1d48709a 100644
--- a/synapse/replication/slave/storage/directory.py
+++ b/synapse/replication/slave/storage/directory.py
@@ -13,9 +13,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import BaseSlavedStore
 from synapse.storage.directory import DirectoryWorkerStore
 
+from ._base import BaseSlavedStore
+
 
 class DirectoryStore(DirectoryWorkerStore, BaseSlavedStore):
     pass
diff --git a/synapse/replication/slave/storage/events.py b/synapse/replication/slave/storage/events.py
index 97d3196633..bdb5eee4af 100644
--- a/synapse/replication/slave/storage/events.py
+++ b/synapse/replication/slave/storage/events.py
@@ -20,10 +20,11 @@ from synapse.storage.event_federation import EventFederationWorkerStore
 from synapse.storage.event_push_actions import EventPushActionsWorkerStore
 from synapse.storage.events_worker import EventsWorkerStore
 from synapse.storage.roommember import RoomMemberWorkerStore
+from synapse.storage.signatures import SignatureWorkerStore
 from synapse.storage.state import StateGroupWorkerStore
 from synapse.storage.stream import StreamWorkerStore
-from synapse.storage.signatures import SignatureWorkerStore
 from synapse.storage.user_erasure_store import UserErasureWorkerStore
+
 from ._base import BaseSlavedStore
 from ._slaved_id_tracker import SlavedIdTracker
 
diff --git a/synapse/replication/slave/storage/filtering.py b/synapse/replication/slave/storage/filtering.py
index 819ed62881..456a14cd5c 100644
--- a/synapse/replication/slave/storage/filtering.py
+++ b/synapse/replication/slave/storage/filtering.py
@@ -13,9 +13,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import BaseSlavedStore
 from synapse.storage.filtering import FilteringStore
 
+from ._base import BaseSlavedStore
+
 
 class SlavedFilteringStore(BaseSlavedStore):
     def __init__(self, db_conn, hs):
diff --git a/synapse/replication/slave/storage/groups.py b/synapse/replication/slave/storage/groups.py
index 0bc4bce5b0..5777f07c8d 100644
--- a/synapse/replication/slave/storage/groups.py
+++ b/synapse/replication/slave/storage/groups.py
@@ -13,11 +13,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import BaseSlavedStore
-from ._slaved_id_tracker import SlavedIdTracker
 from synapse.storage import DataStore
 from synapse.util.caches.stream_change_cache import StreamChangeCache
 
+from ._base import BaseSlavedStore
+from ._slaved_id_tracker import SlavedIdTracker
+
 
 class SlavedGroupServerStore(BaseSlavedStore):
     def __init__(self, db_conn, hs):
diff --git a/synapse/replication/slave/storage/keys.py b/synapse/replication/slave/storage/keys.py
index dd2ae49e48..05ed168463 100644
--- a/synapse/replication/slave/storage/keys.py
+++ b/synapse/replication/slave/storage/keys.py
@@ -13,10 +13,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import BaseSlavedStore
 from synapse.storage import DataStore
 from synapse.storage.keys import KeyStore
 
+from ._base import BaseSlavedStore
+
 
 class SlavedKeyStore(BaseSlavedStore):
     _get_server_verify_key = KeyStore.__dict__[
diff --git a/synapse/replication/slave/storage/presence.py b/synapse/replication/slave/storage/presence.py
index cfb9280181..80b744082a 100644
--- a/synapse/replication/slave/storage/presence.py
+++ b/synapse/replication/slave/storage/presence.py
@@ -13,12 +13,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import BaseSlavedStore
-from ._slaved_id_tracker import SlavedIdTracker
-
-from synapse.util.caches.stream_change_cache import StreamChangeCache
 from synapse.storage import DataStore
 from synapse.storage.presence import PresenceStore
+from synapse.util.caches.stream_change_cache import StreamChangeCache
+
+from ._base import BaseSlavedStore
+from ._slaved_id_tracker import SlavedIdTracker
 
 
 class SlavedPresenceStore(BaseSlavedStore):
diff --git a/synapse/replication/slave/storage/push_rule.py b/synapse/replication/slave/storage/push_rule.py
index bb2c40b6e3..f0200c1e98 100644
--- a/synapse/replication/slave/storage/push_rule.py
+++ b/synapse/replication/slave/storage/push_rule.py
@@ -14,10 +14,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from .events import SlavedEventStore
-from ._slaved_id_tracker import SlavedIdTracker
 from synapse.storage.push_rule import PushRulesWorkerStore
 
+from ._slaved_id_tracker import SlavedIdTracker
+from .events import SlavedEventStore
+
 
 class SlavedPushRuleStore(PushRulesWorkerStore, SlavedEventStore):
     def __init__(self, db_conn, hs):
diff --git a/synapse/replication/slave/storage/pushers.py b/synapse/replication/slave/storage/pushers.py
index a7cd5a7291..3b2213c0d4 100644
--- a/synapse/replication/slave/storage/pushers.py
+++ b/synapse/replication/slave/storage/pushers.py
@@ -14,11 +14,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from synapse.storage.pusher import PusherWorkerStore
+
 from ._base import BaseSlavedStore
 from ._slaved_id_tracker import SlavedIdTracker
 
-from synapse.storage.pusher import PusherWorkerStore
-
 
 class SlavedPusherStore(PusherWorkerStore, BaseSlavedStore):
 
diff --git a/synapse/replication/slave/storage/receipts.py b/synapse/replication/slave/storage/receipts.py
index 1647072f65..7ab12b850f 100644
--- a/synapse/replication/slave/storage/receipts.py
+++ b/synapse/replication/slave/storage/receipts.py
@@ -14,11 +14,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from synapse.storage.receipts import ReceiptsWorkerStore
+
 from ._base import BaseSlavedStore
 from ._slaved_id_tracker import SlavedIdTracker
 
-from synapse.storage.receipts import ReceiptsWorkerStore
-
 # So, um, we want to borrow a load of functions intended for reading from
 # a DataStore, but we don't want to take functions that either write to the
 # DataStore or are cached and don't have cache invalidation logic.
diff --git a/synapse/replication/slave/storage/registration.py b/synapse/replication/slave/storage/registration.py
index 7323bf0f1e..408d91df1c 100644
--- a/synapse/replication/slave/storage/registration.py
+++ b/synapse/replication/slave/storage/registration.py
@@ -13,9 +13,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import BaseSlavedStore
 from synapse.storage.registration import RegistrationWorkerStore
 
+from ._base import BaseSlavedStore
+
 
 class SlavedRegistrationStore(RegistrationWorkerStore, BaseSlavedStore):
     pass
diff --git a/synapse/replication/slave/storage/room.py b/synapse/replication/slave/storage/room.py
index 5ae1670157..0cb474928c 100644
--- a/synapse/replication/slave/storage/room.py
+++ b/synapse/replication/slave/storage/room.py
@@ -13,8 +13,9 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import BaseSlavedStore
 from synapse.storage.room import RoomWorkerStore
+
+from ._base import BaseSlavedStore
 from ._slaved_id_tracker import SlavedIdTracker
 
 
diff --git a/synapse/replication/slave/storage/transactions.py b/synapse/replication/slave/storage/transactions.py
index fbb58f35da..9c9a5eadd9 100644
--- a/synapse/replication/slave/storage/transactions.py
+++ b/synapse/replication/slave/storage/transactions.py
@@ -13,10 +13,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import BaseSlavedStore
 from synapse.storage import DataStore
 from synapse.storage.transactions import TransactionStore
 
+from ._base import BaseSlavedStore
+
 
 class TransactionStore(BaseSlavedStore):
     get_destination_retry_timings = TransactionStore.__dict__[
diff --git a/synapse/replication/tcp/client.py b/synapse/replication/tcp/client.py
index bb852b00af..e592ab57bf 100644
--- a/synapse/replication/tcp/client.py
+++ b/synapse/replication/tcp/client.py
@@ -15,17 +15,20 @@
 """A replication client for use by synapse workers.
 """
 
+import logging
+
 from twisted.internet import defer
 from twisted.internet.protocol import ReconnectingClientFactory
 
 from .commands import (
-    FederationAckCommand, UserSyncCommand, RemovePusherCommand, InvalidateCacheCommand,
+    FederationAckCommand,
+    InvalidateCacheCommand,
+    RemovePusherCommand,
     UserIpCommand,
+    UserSyncCommand,
 )
 from .protocol import ClientReplicationStreamProtocol
 
-import logging
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/replication/tcp/protocol.py b/synapse/replication/tcp/protocol.py
index 171a698e14..dec5ac0913 100644
--- a/synapse/replication/tcp/protocol.py
+++ b/synapse/replication/tcp/protocol.py
@@ -49,29 +49,37 @@ indicate which side is sending, these are *not* included on the wire::
     * connection closed by server *
 """
 
+import fcntl
+import logging
+import struct
+from collections import defaultdict
+
+from six import iteritems, iterkeys
+
+from prometheus_client import Counter
+
 from twisted.internet import defer
 from twisted.protocols.basic import LineOnlyReceiver
 from twisted.python.failure import Failure
 
-from .commands import (
-    COMMAND_MAP, VALID_CLIENT_COMMANDS, VALID_SERVER_COMMANDS,
-    ErrorCommand, ServerCommand, RdataCommand, PositionCommand, PingCommand,
-    NameCommand, ReplicateCommand, UserSyncCommand, SyncCommand,
-)
-from .streams import STREAMS_MAP
-
 from synapse.metrics import LaterGauge
 from synapse.util.stringutils import random_string
 
-from prometheus_client import Counter
-
-from collections import defaultdict
-
-from six import iterkeys, iteritems
-
-import logging
-import struct
-import fcntl
+from .commands import (
+    COMMAND_MAP,
+    VALID_CLIENT_COMMANDS,
+    VALID_SERVER_COMMANDS,
+    ErrorCommand,
+    NameCommand,
+    PingCommand,
+    PositionCommand,
+    RdataCommand,
+    ReplicateCommand,
+    ServerCommand,
+    SyncCommand,
+    UserSyncCommand,
+)
+from .streams import STREAMS_MAP
 
 connection_close_counter = Counter(
     "synapse_replication_tcp_protocol_close_reason", "", ["reason_type"])
diff --git a/synapse/replication/tcp/resource.py b/synapse/replication/tcp/resource.py
index 95ad8c1b4c..611fb66e1d 100644
--- a/synapse/replication/tcp/resource.py
+++ b/synapse/replication/tcp/resource.py
@@ -15,19 +15,20 @@
 """The server side of the replication stream.
 """
 
+import logging
+
+from six import itervalues
+
+from prometheus_client import Counter
+
 from twisted.internet import defer
 from twisted.internet.protocol import Factory
 
-from .streams import STREAMS_MAP, FederationStream
-from .protocol import ServerReplicationStreamProtocol
-
-from synapse.util.metrics import Measure, measure_func
 from synapse.metrics import LaterGauge
+from synapse.util.metrics import Measure, measure_func
 
-import logging
-
-from prometheus_client import Counter
-from six import itervalues
+from .protocol import ServerReplicationStreamProtocol
+from .streams import STREAMS_MAP, FederationStream
 
 stream_updates_counter = Counter("synapse_replication_tcp_resource_stream_updates",
                                  "", ["stream_name"])
diff --git a/synapse/replication/tcp/streams.py b/synapse/replication/tcp/streams.py
index 07d99dd63c..ab65a6792e 100644
--- a/synapse/replication/tcp/streams.py
+++ b/synapse/replication/tcp/streams.py
@@ -24,11 +24,10 @@ Each stream is defined by the following information:
     update_function:    The function that returns a list of updates between two tokens
 """
 
-from twisted.internet import defer
+import logging
 from collections import namedtuple
 
-import logging
-
+from twisted.internet import defer
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/rest/__init__.py b/synapse/rest/__init__.py
index 16f5a73b95..75c2a4ec8e 100644
--- a/synapse/rest/__init__.py
+++ b/synapse/rest/__init__.py
@@ -13,49 +13,34 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.rest.client import (
-    versions,
-)
-
-from synapse.rest.client.v1 import (
-    room,
-    events,
-    profile,
-    presence,
-    initial_sync,
-    directory,
-    voip,
-    admin,
-    pusher,
-    push_rule,
-    register as v1_register,
-    login as v1_login,
-    logout,
-)
-
-from synapse.rest.client.v2_alpha import (
-    sync,
-    filter,
-    account,
-    register,
-    auth,
-    receipts,
-    read_marker,
-    keys,
-    tokenrefresh,
-    tags,
-    account_data,
-    report_event,
-    openid,
-    notifications,
-    devices,
-    thirdparty,
-    sendtodevice,
-    user_directory,
-    groups,
-)
-
 from synapse.http.server import JsonResource
+from synapse.rest.client import versions
+from synapse.rest.client.v1 import admin, directory, events, initial_sync
+from synapse.rest.client.v1 import login as v1_login
+from synapse.rest.client.v1 import logout, presence, profile, push_rule, pusher
+from synapse.rest.client.v1 import register as v1_register
+from synapse.rest.client.v1 import room, voip
+from synapse.rest.client.v2_alpha import (
+    account,
+    account_data,
+    auth,
+    devices,
+    filter,
+    groups,
+    keys,
+    notifications,
+    openid,
+    read_marker,
+    receipts,
+    register,
+    report_event,
+    sendtodevice,
+    sync,
+    tags,
+    thirdparty,
+    tokenrefresh,
+    user_directory,
+)
 
 
 class ClientRestResource(JsonResource):
diff --git a/synapse/rest/client/v1/admin.py b/synapse/rest/client/v1/admin.py
index 638a7dba34..fc4a5597ba 100644
--- a/synapse/rest/client/v1/admin.py
+++ b/synapse/rest/client/v1/admin.py
@@ -14,19 +14,19 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer
+import logging
 
 from six.moves import http_client
 
+from twisted.internet import defer
+
 from synapse.api.constants import Membership
-from synapse.api.errors import AuthError, SynapseError, Codes, NotFoundError
-from synapse.types import UserID, create_requester
+from synapse.api.errors import AuthError, Codes, NotFoundError, SynapseError
 from synapse.http.servlet import parse_json_object_from_request
+from synapse.types import UserID, create_requester
 
 from .base import ClientV1RestServlet, client_path_patterns
 
-import logging
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/rest/client/v1/base.py b/synapse/rest/client/v1/base.py
index 197335d7aa..dde02328c3 100644
--- a/synapse/rest/client/v1/base.py
+++ b/synapse/rest/client/v1/base.py
@@ -16,14 +16,12 @@
 """This module contains base REST classes for constructing client v1 servlets.
 """
 
-from synapse.http.servlet import RestServlet
-from synapse.api.urls import CLIENT_PREFIX
-from synapse.rest.client.transactions import HttpTransactionCache
-
+import logging
 import re
 
-import logging
-
+from synapse.api.urls import CLIENT_PREFIX
+from synapse.http.servlet import RestServlet
+from synapse.rest.client.transactions import HttpTransactionCache
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/rest/client/v1/directory.py b/synapse/rest/client/v1/directory.py
index 1c3933380f..4fdbb83815 100644
--- a/synapse/rest/client/v1/directory.py
+++ b/synapse/rest/client/v1/directory.py
@@ -14,16 +14,15 @@
 # limitations under the License.
 
 
-from twisted.internet import defer
-
-from synapse.api.errors import AuthError, SynapseError, Codes
-from synapse.types import RoomAlias
-from synapse.http.servlet import parse_json_object_from_request
-
-from .base import ClientV1RestServlet, client_path_patterns
-
 import logging
 
+from twisted.internet import defer
+
+from synapse.api.errors import AuthError, Codes, SynapseError
+from synapse.http.servlet import parse_json_object_from_request
+from synapse.types import RoomAlias
+
+from .base import ClientV1RestServlet, client_path_patterns
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/rest/client/v1/events.py b/synapse/rest/client/v1/events.py
index 701b6f549b..b70c9c2806 100644
--- a/synapse/rest/client/v1/events.py
+++ b/synapse/rest/client/v1/events.py
@@ -14,15 +14,15 @@
 # limitations under the License.
 
 """This module contains REST servlets to do with event streaming, /events."""
+import logging
+
 from twisted.internet import defer
 
 from synapse.api.errors import SynapseError
-from synapse.streams.config import PaginationConfig
-from .base import ClientV1RestServlet, client_path_patterns
 from synapse.events.utils import serialize_event
+from synapse.streams.config import PaginationConfig
 
-import logging
-
+from .base import ClientV1RestServlet, client_path_patterns
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/rest/client/v1/initial_sync.py b/synapse/rest/client/v1/initial_sync.py
index 478e21eea8..fbe8cb2023 100644
--- a/synapse/rest/client/v1/initial_sync.py
+++ b/synapse/rest/client/v1/initial_sync.py
@@ -16,6 +16,7 @@
 from twisted.internet import defer
 
 from synapse.streams.config import PaginationConfig
+
 from .base import ClientV1RestServlet, client_path_patterns
 
 
diff --git a/synapse/rest/client/v1/login.py b/synapse/rest/client/v1/login.py
index 88ca5184cd..cb85fa1436 100644
--- a/synapse/rest/client/v1/login.py
+++ b/synapse/rest/client/v1/login.py
@@ -13,31 +13,27 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer
+import logging
+import urllib
+import xml.etree.ElementTree as ET
 
-from synapse.api.errors import SynapseError, LoginError, Codes
-from synapse.types import UserID
+from six.moves.urllib import parse as urlparse
+
+from canonicaljson import json
+from saml2 import BINDING_HTTP_POST, config
+from saml2.client import Saml2Client
+
+from twisted.internet import defer
+from twisted.web.client import PartialDownloadError
+
+from synapse.api.errors import Codes, LoginError, SynapseError
 from synapse.http.server import finish_request
 from synapse.http.servlet import parse_json_object_from_request
+from synapse.types import UserID
 from synapse.util.msisdn import phone_number_to_msisdn
 
 from .base import ClientV1RestServlet, client_path_patterns
 
-from canonicaljson import json
-
-import urllib
-from six.moves.urllib import parse as urlparse
-
-import logging
-from saml2 import BINDING_HTTP_POST
-from saml2 import config
-from saml2.client import Saml2Client
-
-import xml.etree.ElementTree as ET
-
-from twisted.web.client import PartialDownloadError
-
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/rest/client/v1/logout.py b/synapse/rest/client/v1/logout.py
index e092158cb7..05a8ecfcd8 100644
--- a/synapse/rest/client/v1/logout.py
+++ b/synapse/rest/client/v1/logout.py
@@ -13,6 +13,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import logging
+
 from twisted.internet import defer
 
 from synapse.api.auth import get_access_token_from_request
@@ -20,9 +22,6 @@ from synapse.api.errors import AuthError
 
 from .base import ClientV1RestServlet, client_path_patterns
 
-import logging
-
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/rest/client/v1/presence.py b/synapse/rest/client/v1/presence.py
index a975666d12..cb61bfcb21 100644
--- a/synapse/rest/client/v1/presence.py
+++ b/synapse/rest/client/v1/presence.py
@@ -15,17 +15,18 @@
 
 """ This module contains REST servlets to do with presence: /presence/<paths>
 """
-from twisted.internet import defer
-
-from synapse.api.errors import SynapseError, AuthError
-from synapse.types import UserID
-from synapse.handlers.presence import format_user_presence_state
-from synapse.http.servlet import parse_json_object_from_request
-from .base import ClientV1RestServlet, client_path_patterns
+import logging
 
 from six import string_types
 
-import logging
+from twisted.internet import defer
+
+from synapse.api.errors import AuthError, SynapseError
+from synapse.handlers.presence import format_user_presence_state
+from synapse.http.servlet import parse_json_object_from_request
+from synapse.types import UserID
+
+from .base import ClientV1RestServlet, client_path_patterns
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/rest/client/v1/profile.py b/synapse/rest/client/v1/profile.py
index e4e3611a14..a23edd8fe5 100644
--- a/synapse/rest/client/v1/profile.py
+++ b/synapse/rest/client/v1/profile.py
@@ -16,9 +16,10 @@
 """ This module contains REST servlets to do with profile: /profile/<paths> """
 from twisted.internet import defer
 
-from .base import ClientV1RestServlet, client_path_patterns
-from synapse.types import UserID
 from synapse.http.servlet import parse_json_object_from_request
+from synapse.types import UserID
+
+from .base import ClientV1RestServlet, client_path_patterns
 
 
 class ProfileDisplaynameRestServlet(ClientV1RestServlet):
diff --git a/synapse/rest/client/v1/push_rule.py b/synapse/rest/client/v1/push_rule.py
index 6bb4821ec6..0df7ce570f 100644
--- a/synapse/rest/client/v1/push_rule.py
+++ b/synapse/rest/client/v1/push_rule.py
@@ -16,16 +16,18 @@
 from twisted.internet import defer
 
 from synapse.api.errors import (
-    SynapseError, UnrecognizedRequestError, NotFoundError, StoreError
+    NotFoundError,
+    StoreError,
+    SynapseError,
+    UnrecognizedRequestError,
 )
-from .base import ClientV1RestServlet, client_path_patterns
-from synapse.storage.push_rule import (
-    InconsistentRuleException, RuleNotFoundException
-)
-from synapse.push.clientformat import format_push_rules_for_user
-from synapse.push.baserules import BASE_RULE_IDS
-from synapse.push.rulekinds import PRIORITY_CLASS_MAP
 from synapse.http.servlet import parse_json_value_from_request
+from synapse.push.baserules import BASE_RULE_IDS
+from synapse.push.clientformat import format_push_rules_for_user
+from synapse.push.rulekinds import PRIORITY_CLASS_MAP
+from synapse.storage.push_rule import InconsistentRuleException, RuleNotFoundException
+
+from .base import ClientV1RestServlet, client_path_patterns
 
 
 class PushRuleRestServlet(ClientV1RestServlet):
diff --git a/synapse/rest/client/v1/pusher.py b/synapse/rest/client/v1/pusher.py
index 40e523cc5f..1581f88db5 100644
--- a/synapse/rest/client/v1/pusher.py
+++ b/synapse/rest/client/v1/pusher.py
@@ -13,20 +13,21 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import logging
+
 from twisted.internet import defer
 
-from synapse.api.errors import SynapseError, Codes
-from synapse.push import PusherConfigException
-from synapse.http.servlet import (
-    parse_json_object_from_request, parse_string, RestServlet
-)
+from synapse.api.errors import Codes, StoreError, SynapseError
 from synapse.http.server import finish_request
-from synapse.api.errors import StoreError
+from synapse.http.servlet import (
+    RestServlet,
+    parse_json_object_from_request,
+    parse_string,
+)
+from synapse.push import PusherConfigException
 
 from .base import ClientV1RestServlet, client_path_patterns
 
-import logging
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/rest/client/v1/register.py b/synapse/rest/client/v1/register.py
index c10320dedf..3ce5f8b726 100644
--- a/synapse/rest/client/v1/register.py
+++ b/synapse/rest/client/v1/register.py
@@ -14,21 +14,22 @@
 # limitations under the License.
 
 """This module contains REST servlets to do with registration: /register"""
+import hmac
+import logging
+from hashlib import sha1
+
+from six import string_types
+
 from twisted.internet import defer
 
-from synapse.api.errors import SynapseError, Codes
-from synapse.api.constants import LoginType
-from synapse.api.auth import get_access_token_from_request
-from .base import ClientV1RestServlet, client_path_patterns
 import synapse.util.stringutils as stringutils
+from synapse.api.auth import get_access_token_from_request
+from synapse.api.constants import LoginType
+from synapse.api.errors import Codes, SynapseError
 from synapse.http.servlet import parse_json_object_from_request
 from synapse.types import create_requester
 
-from hashlib import sha1
-import hmac
-import logging
-
-from six import string_types
+from .base import ClientV1RestServlet, client_path_patterns
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/rest/client/v1/room.py b/synapse/rest/client/v1/room.py
index e6ae5db79b..2470db52ba 100644
--- a/synapse/rest/client/v1/room.py
+++ b/synapse/rest/client/v1/room.py
@@ -15,24 +15,28 @@
 # limitations under the License.
 
 """ This module contains REST servlets to do with rooms: /rooms/<paths> """
-from twisted.internet import defer
-
-from .base import ClientV1RestServlet, client_path_patterns
-from synapse.api.errors import SynapseError, Codes, AuthError
-from synapse.streams.config import PaginationConfig
-from synapse.api.constants import EventTypes, Membership
-from synapse.api.filtering import Filter
-from synapse.types import UserID, RoomID, RoomAlias, ThirdPartyInstanceID
-from synapse.events.utils import serialize_event, format_event_for_client_v2
-from synapse.http.servlet import (
-    parse_json_object_from_request, parse_string, parse_integer
-)
+import logging
 
 from six.moves.urllib import parse as urlparse
 
-import logging
 from canonicaljson import json
 
+from twisted.internet import defer
+
+from synapse.api.constants import EventTypes, Membership
+from synapse.api.errors import AuthError, Codes, SynapseError
+from synapse.api.filtering import Filter
+from synapse.events.utils import format_event_for_client_v2, serialize_event
+from synapse.http.servlet import (
+    parse_integer,
+    parse_json_object_from_request,
+    parse_string,
+)
+from synapse.streams.config import PaginationConfig
+from synapse.types import RoomAlias, RoomID, ThirdPartyInstanceID, UserID
+
+from .base import ClientV1RestServlet, client_path_patterns
+
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/rest/client/v1/voip.py b/synapse/rest/client/v1/voip.py
index c43b30b73a..62f4c3d93e 100644
--- a/synapse/rest/client/v1/voip.py
+++ b/synapse/rest/client/v1/voip.py
@@ -13,16 +13,15 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import base64
+import hashlib
+import hmac
+
 from twisted.internet import defer
 
 from .base import ClientV1RestServlet, client_path_patterns
 
 
-import hmac
-import hashlib
-import base64
-
-
 class VoipRestServlet(ClientV1RestServlet):
     PATTERNS = client_path_patterns("/voip/turnServer$")
 
diff --git a/synapse/rest/client/v2_alpha/account.py b/synapse/rest/client/v2_alpha/account.py
index 80dbc3c92e..528c1f43f9 100644
--- a/synapse/rest/client/v2_alpha/account.py
+++ b/synapse/rest/client/v2_alpha/account.py
@@ -17,17 +17,20 @@
 import logging
 
 from six.moves import http_client
+
 from twisted.internet import defer
 
 from synapse.api.auth import has_access_token
 from synapse.api.constants import LoginType
 from synapse.api.errors import Codes, SynapseError
 from synapse.http.servlet import (
-    RestServlet, assert_params_in_request,
+    RestServlet,
+    assert_params_in_request,
     parse_json_object_from_request,
 )
 from synapse.util.msisdn import phone_number_to_msisdn
 from synapse.util.threepids import check_3pid_allowed
+
 from ._base import client_v2_patterns, interactive_auth_handler
 
 logger = logging.getLogger(__name__)
diff --git a/synapse/rest/client/v2_alpha/account_data.py b/synapse/rest/client/v2_alpha/account_data.py
index 0e0a187efd..371e9aa354 100644
--- a/synapse/rest/client/v2_alpha/account_data.py
+++ b/synapse/rest/client/v2_alpha/account_data.py
@@ -13,14 +13,14 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import client_v2_patterns
-
-from synapse.http.servlet import RestServlet, parse_json_object_from_request
-from synapse.api.errors import AuthError, SynapseError
+import logging
 
 from twisted.internet import defer
 
-import logging
+from synapse.api.errors import AuthError, SynapseError
+from synapse.http.servlet import RestServlet, parse_json_object_from_request
+
+from ._base import client_v2_patterns
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/rest/client/v2_alpha/auth.py b/synapse/rest/client/v2_alpha/auth.py
index d6f3a19648..bd8b5f4afa 100644
--- a/synapse/rest/client/v2_alpha/auth.py
+++ b/synapse/rest/client/v2_alpha/auth.py
@@ -13,6 +13,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import logging
+
 from twisted.internet import defer
 
 from synapse.api.constants import LoginType
@@ -23,9 +25,6 @@ from synapse.http.servlet import RestServlet
 
 from ._base import client_v2_patterns
 
-import logging
-
-
 logger = logging.getLogger(__name__)
 
 RECAPTCHA_TEMPLATE = """
diff --git a/synapse/rest/client/v2_alpha/devices.py b/synapse/rest/client/v2_alpha/devices.py
index 35d58b367a..09f6a8efe3 100644
--- a/synapse/rest/client/v2_alpha/devices.py
+++ b/synapse/rest/client/v2_alpha/devices.py
@@ -19,6 +19,7 @@ from twisted.internet import defer
 
 from synapse.api import errors
 from synapse.http import servlet
+
 from ._base import client_v2_patterns, interactive_auth_handler
 
 logger = logging.getLogger(__name__)
diff --git a/synapse/rest/client/v2_alpha/filter.py b/synapse/rest/client/v2_alpha/filter.py
index 1b9dc4528d..ae86728879 100644
--- a/synapse/rest/client/v2_alpha/filter.py
+++ b/synapse/rest/client/v2_alpha/filter.py
@@ -13,17 +13,15 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import logging
+
 from twisted.internet import defer
 
-from synapse.api.errors import AuthError, SynapseError, StoreError, Codes
+from synapse.api.errors import AuthError, Codes, StoreError, SynapseError
 from synapse.http.servlet import RestServlet, parse_json_object_from_request
 from synapse.types import UserID
 
-from ._base import client_v2_patterns
-from ._base import set_timeline_upper_limit
-
-import logging
-
+from ._base import client_v2_patterns, set_timeline_upper_limit
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/rest/client/v2_alpha/groups.py b/synapse/rest/client/v2_alpha/groups.py
index 3bb1ec2af6..21e02c07c0 100644
--- a/synapse/rest/client/v2_alpha/groups.py
+++ b/synapse/rest/client/v2_alpha/groups.py
@@ -14,6 +14,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import logging
+
 from twisted.internet import defer
 
 from synapse.http.servlet import RestServlet, parse_json_object_from_request
@@ -21,8 +23,6 @@ from synapse.types import GroupID
 
 from ._base import client_v2_patterns
 
-import logging
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/rest/client/v2_alpha/keys.py b/synapse/rest/client/v2_alpha/keys.py
index 3cc87ea63f..8486086b51 100644
--- a/synapse/rest/client/v2_alpha/keys.py
+++ b/synapse/rest/client/v2_alpha/keys.py
@@ -19,10 +19,13 @@ from twisted.internet import defer
 
 from synapse.api.errors import SynapseError
 from synapse.http.servlet import (
-    RestServlet, parse_json_object_from_request, parse_integer
+    RestServlet,
+    parse_integer,
+    parse_json_object_from_request,
+    parse_string,
 )
-from synapse.http.servlet import parse_string
 from synapse.types import StreamToken
+
 from ._base import client_v2_patterns
 
 logger = logging.getLogger(__name__)
diff --git a/synapse/rest/client/v2_alpha/notifications.py b/synapse/rest/client/v2_alpha/notifications.py
index 66583d6778..2a6ea3df5f 100644
--- a/synapse/rest/client/v2_alpha/notifications.py
+++ b/synapse/rest/client/v2_alpha/notifications.py
@@ -13,19 +13,18 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import logging
+
 from twisted.internet import defer
 
-from synapse.http.servlet import (
-    RestServlet, parse_string, parse_integer
-)
 from synapse.events.utils import (
-    serialize_event, format_event_for_client_v2_without_room_id,
+    format_event_for_client_v2_without_room_id,
+    serialize_event,
 )
+from synapse.http.servlet import RestServlet, parse_integer, parse_string
 
 from ._base import client_v2_patterns
 
-import logging
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/rest/client/v2_alpha/openid.py b/synapse/rest/client/v2_alpha/openid.py
index aa1cae8e1e..01c90aa2a3 100644
--- a/synapse/rest/client/v2_alpha/openid.py
+++ b/synapse/rest/client/v2_alpha/openid.py
@@ -14,15 +14,15 @@
 # limitations under the License.
 
 
-from ._base import client_v2_patterns
-
-from synapse.http.servlet import RestServlet, parse_json_object_from_request
-from synapse.api.errors import AuthError
-from synapse.util.stringutils import random_string
+import logging
 
 from twisted.internet import defer
 
-import logging
+from synapse.api.errors import AuthError
+from synapse.http.servlet import RestServlet, parse_json_object_from_request
+from synapse.util.stringutils import random_string
+
+from ._base import client_v2_patterns
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/rest/client/v2_alpha/read_marker.py b/synapse/rest/client/v2_alpha/read_marker.py
index 2f8784fe06..a6e582a5ae 100644
--- a/synapse/rest/client/v2_alpha/read_marker.py
+++ b/synapse/rest/client/v2_alpha/read_marker.py
@@ -13,14 +13,14 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import logging
+
 from twisted.internet import defer
 
 from synapse.http.servlet import RestServlet, parse_json_object_from_request
+
 from ._base import client_v2_patterns
 
-import logging
-
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/rest/client/v2_alpha/receipts.py b/synapse/rest/client/v2_alpha/receipts.py
index 1fbff2edd8..de370cac45 100644
--- a/synapse/rest/client/v2_alpha/receipts.py
+++ b/synapse/rest/client/v2_alpha/receipts.py
@@ -13,15 +13,15 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import logging
+
 from twisted.internet import defer
 
 from synapse.api.errors import SynapseError
 from synapse.http.servlet import RestServlet
+
 from ._base import client_v2_patterns
 
-import logging
-
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/rest/client/v2_alpha/register.py b/synapse/rest/client/v2_alpha/register.py
index 97e7c0f7c6..896650d5a5 100644
--- a/synapse/rest/client/v2_alpha/register.py
+++ b/synapse/rest/client/v2_alpha/register.py
@@ -14,29 +14,31 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import hmac
+import logging
+from hashlib import sha1
+
+from six import string_types
+
 from twisted.internet import defer
 
 import synapse
 import synapse.types
 from synapse.api.auth import get_access_token_from_request, has_access_token
 from synapse.api.constants import LoginType
-from synapse.api.errors import SynapseError, Codes, UnrecognizedRequestError
+from synapse.api.errors import Codes, SynapseError, UnrecognizedRequestError
 from synapse.http.servlet import (
-    RestServlet, parse_json_object_from_request, assert_params_in_request, parse_string
+    RestServlet,
+    assert_params_in_request,
+    parse_json_object_from_request,
+    parse_string,
 )
 from synapse.util.msisdn import phone_number_to_msisdn
+from synapse.util.ratelimitutils import FederationRateLimiter
 from synapse.util.threepids import check_3pid_allowed
 
 from ._base import client_v2_patterns, interactive_auth_handler
 
-import logging
-import hmac
-from hashlib import sha1
-from synapse.util.ratelimitutils import FederationRateLimiter
-
-from six import string_types
-
-
 # We ought to be using hmac.compare_digest() but on older pythons it doesn't
 # exist. It's a _really minor_ security flaw to use plain string comparison
 # because the timing attack is so obscured by all the other code here it's
diff --git a/synapse/rest/client/v2_alpha/report_event.py b/synapse/rest/client/v2_alpha/report_event.py
index 8903e12405..08bb8e04fd 100644
--- a/synapse/rest/client/v2_alpha/report_event.py
+++ b/synapse/rest/client/v2_alpha/report_event.py
@@ -13,14 +13,14 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import logging
+
 from twisted.internet import defer
 
 from synapse.http.servlet import RestServlet, parse_json_object_from_request
+
 from ._base import client_v2_patterns
 
-import logging
-
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/rest/client/v2_alpha/sync.py b/synapse/rest/client/v2_alpha/sync.py
index d2aa47b326..8aa06faf23 100644
--- a/synapse/rest/client/v2_alpha/sync.py
+++ b/synapse/rest/client/v2_alpha/sync.py
@@ -13,28 +13,27 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer
-
-from synapse.http.servlet import (
-    RestServlet, parse_string, parse_integer, parse_boolean
-)
-from synapse.handlers.presence import format_user_presence_state
-from synapse.handlers.sync import SyncConfig
-from synapse.types import StreamToken
-from synapse.events.utils import (
-    serialize_event, format_event_for_client_v2_without_room_id,
-)
-from synapse.api.filtering import FilterCollection, DEFAULT_FILTER_COLLECTION
-from synapse.api.errors import SynapseError
-from synapse.api.constants import PresenceState
-from ._base import client_v2_patterns
-from ._base import set_timeline_upper_limit
-
 import itertools
 import logging
 
 from canonicaljson import json
 
+from twisted.internet import defer
+
+from synapse.api.constants import PresenceState
+from synapse.api.errors import SynapseError
+from synapse.api.filtering import DEFAULT_FILTER_COLLECTION, FilterCollection
+from synapse.events.utils import (
+    format_event_for_client_v2_without_room_id,
+    serialize_event,
+)
+from synapse.handlers.presence import format_user_presence_state
+from synapse.handlers.sync import SyncConfig
+from synapse.http.servlet import RestServlet, parse_boolean, parse_integer, parse_string
+from synapse.types import StreamToken
+
+from ._base import client_v2_patterns, set_timeline_upper_limit
+
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/rest/client/v2_alpha/tags.py b/synapse/rest/client/v2_alpha/tags.py
index dac8603b07..4fea614e95 100644
--- a/synapse/rest/client/v2_alpha/tags.py
+++ b/synapse/rest/client/v2_alpha/tags.py
@@ -13,14 +13,14 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import client_v2_patterns
-
-from synapse.http.servlet import RestServlet, parse_json_object_from_request
-from synapse.api.errors import AuthError
+import logging
 
 from twisted.internet import defer
 
-import logging
+from synapse.api.errors import AuthError
+from synapse.http.servlet import RestServlet, parse_json_object_from_request
+
+from ._base import client_v2_patterns
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/rest/client/v2_alpha/thirdparty.py b/synapse/rest/client/v2_alpha/thirdparty.py
index 6773b9ba60..d9d379182e 100644
--- a/synapse/rest/client/v2_alpha/thirdparty.py
+++ b/synapse/rest/client/v2_alpha/thirdparty.py
@@ -20,6 +20,7 @@ from twisted.internet import defer
 
 from synapse.api.constants import ThirdPartyEntityKind
 from synapse.http.servlet import RestServlet
+
 from ._base import client_v2_patterns
 
 logger = logging.getLogger(__name__)
diff --git a/synapse/rest/client/v2_alpha/user_directory.py b/synapse/rest/client/v2_alpha/user_directory.py
index 2d4a43c353..cac0624ba7 100644
--- a/synapse/rest/client/v2_alpha/user_directory.py
+++ b/synapse/rest/client/v2_alpha/user_directory.py
@@ -19,6 +19,7 @@ from twisted.internet import defer
 
 from synapse.api.errors import SynapseError
 from synapse.http.servlet import RestServlet, parse_json_object_from_request
+
 from ._base import client_v2_patterns
 
 logger = logging.getLogger(__name__)
diff --git a/synapse/rest/client/versions.py b/synapse/rest/client/versions.py
index 2ecb15deee..6ac2987b98 100644
--- a/synapse/rest/client/versions.py
+++ b/synapse/rest/client/versions.py
@@ -13,11 +13,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.http.servlet import RestServlet
-
 import logging
 import re
 
+from synapse.http.servlet import RestServlet
+
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/rest/consent/consent_resource.py b/synapse/rest/consent/consent_resource.py
index 724911d1e6..147ff7d79b 100644
--- a/synapse/rest/consent/consent_resource.py
+++ b/synapse/rest/consent/consent_resource.py
@@ -13,28 +13,26 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from hashlib import sha256
 import hmac
 import logging
+from hashlib import sha256
 from os import path
+
 from six.moves import http_client
 
 import jinja2
 from jinja2 import TemplateNotFound
+
 from twisted.internet import defer
 from twisted.web.resource import Resource
 from twisted.web.server import NOT_DONE_YET
 
-from synapse.api.errors import NotFoundError, SynapseError, StoreError
+from synapse.api.errors import NotFoundError, StoreError, SynapseError
 from synapse.config import ConfigError
-from synapse.http.server import (
-    finish_request,
-    wrap_html_request_handler,
-)
+from synapse.http.server import finish_request, wrap_html_request_handler
 from synapse.http.servlet import parse_string
 from synapse.types import UserID
 
-
 # language to use for the templates. TODO: figure this out from Accept-Language
 TEMPLATE_LANGUAGE = "en"
 
diff --git a/synapse/rest/key/v1/server_key_resource.py b/synapse/rest/key/v1/server_key_resource.py
index 1498d188c1..b9ee6e1c13 100644
--- a/synapse/rest/key/v1/server_key_resource.py
+++ b/synapse/rest/key/v1/server_key_resource.py
@@ -14,14 +14,16 @@
 # limitations under the License.
 
 
-from twisted.web.resource import Resource
-from synapse.http.server import respond_with_json_bytes
-from signedjson.sign import sign_json
-from unpaddedbase64 import encode_base64
-from canonicaljson import encode_canonical_json
-from OpenSSL import crypto
 import logging
 
+from canonicaljson import encode_canonical_json
+from signedjson.sign import sign_json
+from unpaddedbase64 import encode_base64
+
+from OpenSSL import crypto
+from twisted.web.resource import Resource
+
+from synapse.http.server import respond_with_json_bytes
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/rest/key/v2/__init__.py b/synapse/rest/key/v2/__init__.py
index a07224148c..3491fd2118 100644
--- a/synapse/rest/key/v2/__init__.py
+++ b/synapse/rest/key/v2/__init__.py
@@ -14,6 +14,7 @@
 # limitations under the License.
 
 from twisted.web.resource import Resource
+
 from .local_key_resource import LocalKey
 from .remote_key_resource import RemoteKey
 
diff --git a/synapse/rest/key/v2/local_key_resource.py b/synapse/rest/key/v2/local_key_resource.py
index 04775b3c45..ec0ec7b431 100644
--- a/synapse/rest/key/v2/local_key_resource.py
+++ b/synapse/rest/key/v2/local_key_resource.py
@@ -14,13 +14,15 @@
 # limitations under the License.
 
 
-from twisted.web.resource import Resource
-from synapse.http.server import respond_with_json_bytes
-from signedjson.sign import sign_json
-from unpaddedbase64 import encode_base64
-from canonicaljson import encode_canonical_json
 import logging
 
+from canonicaljson import encode_canonical_json
+from signedjson.sign import sign_json
+from unpaddedbase64 import encode_base64
+
+from twisted.web.resource import Resource
+
+from synapse.http.server import respond_with_json_bytes
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/rest/key/v2/remote_key_resource.py b/synapse/rest/key/v2/remote_key_resource.py
index 21b4c1175e..7d67e4b064 100644
--- a/synapse/rest/key/v2/remote_key_resource.py
+++ b/synapse/rest/key/v2/remote_key_resource.py
@@ -12,20 +12,18 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.http.server import (
-    respond_with_json_bytes, wrap_json_request_handler,
-)
-from synapse.http.servlet import parse_integer, parse_json_object_from_request
-from synapse.api.errors import SynapseError, Codes
-from synapse.crypto.keyring import KeyLookupError
+import logging
+from io import BytesIO
 
+from twisted.internet import defer
 from twisted.web.resource import Resource
 from twisted.web.server import NOT_DONE_YET
-from twisted.internet import defer
 
+from synapse.api.errors import Codes, SynapseError
+from synapse.crypto.keyring import KeyLookupError
+from synapse.http.server import respond_with_json_bytes, wrap_json_request_handler
+from synapse.http.servlet import parse_integer, parse_json_object_from_request
 
-from io import BytesIO
-import logging
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/rest/media/v0/content_repository.py b/synapse/rest/media/v0/content_repository.py
index e44d4276d2..f255f2883f 100644
--- a/synapse/rest/media/v0/content_repository.py
+++ b/synapse/rest/media/v0/content_repository.py
@@ -13,22 +13,19 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.http.server import respond_with_json_bytes, finish_request
-
-from synapse.api.errors import (
-    Codes, cs_error
-)
-
-from twisted.protocols.basic import FileSender
-from twisted.web import server, resource
-
-from canonicaljson import json
-
 import base64
 import logging
 import os
 import re
 
+from canonicaljson import json
+
+from twisted.protocols.basic import FileSender
+from twisted.web import resource, server
+
+from synapse.api.errors import Codes, cs_error
+from synapse.http.server import finish_request, respond_with_json_bytes
+
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/rest/media/v1/_base.py b/synapse/rest/media/v1/_base.py
index c0d2f06855..65f4bd2910 100644
--- a/synapse/rest/media/v1/_base.py
+++ b/synapse/rest/media/v1/_base.py
@@ -13,23 +13,20 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.http.server import respond_with_json, finish_request
-from synapse.api.errors import (
-    cs_error, Codes, SynapseError
-)
-from synapse.util import logcontext
+import logging
+import os
+import urllib
+
+from six.moves.urllib import parse as urlparse
 
 from twisted.internet import defer
 from twisted.protocols.basic import FileSender
 
+from synapse.api.errors import Codes, SynapseError, cs_error
+from synapse.http.server import finish_request, respond_with_json
+from synapse.util import logcontext
 from synapse.util.stringutils import is_ascii
 
-import os
-
-import logging
-import urllib
-from six.moves.urllib import parse as urlparse
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/rest/media/v1/download_resource.py b/synapse/rest/media/v1/download_resource.py
index 8cf8820c31..fbfa85f74f 100644
--- a/synapse/rest/media/v1/download_resource.py
+++ b/synapse/rest/media/v1/download_resource.py
@@ -18,11 +18,9 @@ from twisted.internet import defer
 from twisted.web.resource import Resource
 from twisted.web.server import NOT_DONE_YET
 
-from synapse.http.server import (
-    set_cors_headers,
-    wrap_json_request_handler,
-)
 import synapse.http.servlet
+from synapse.http.server import set_cors_headers, wrap_json_request_handler
+
 from ._base import parse_media_id, respond_404
 
 logger = logging.getLogger(__name__)
diff --git a/synapse/rest/media/v1/filepath.py b/synapse/rest/media/v1/filepath.py
index d5164e47e0..c8586fa280 100644
--- a/synapse/rest/media/v1/filepath.py
+++ b/synapse/rest/media/v1/filepath.py
@@ -13,9 +13,9 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import functools
 import os
 import re
-import functools
 
 NEW_FORMAT_ID_RE = re.compile(r"^\d\d\d\d-\d\d-\d\d")
 
diff --git a/synapse/rest/media/v1/identicon_resource.py b/synapse/rest/media/v1/identicon_resource.py
index 66f2b6bd30..a2e391415f 100644
--- a/synapse/rest/media/v1/identicon_resource.py
+++ b/synapse/rest/media/v1/identicon_resource.py
@@ -13,6 +13,7 @@
 # limitations under the License.
 
 from pydenticon import Generator
+
 from twisted.web.resource import Resource
 
 FOREGROUND = [
diff --git a/synapse/rest/media/v1/media_repository.py b/synapse/rest/media/v1/media_repository.py
index 218ba7a083..30242c525a 100644
--- a/synapse/rest/media/v1/media_repository.py
+++ b/synapse/rest/media/v1/media_repository.py
@@ -14,41 +14,42 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer, threads
-import twisted.internet.error
-import twisted.web.http
-from twisted.web.resource import Resource
-
-from ._base import respond_404, FileInfo, respond_with_responder
-from .upload_resource import UploadResource
-from .download_resource import DownloadResource
-from .thumbnail_resource import ThumbnailResource
-from .identicon_resource import IdenticonResource
-from .preview_url_resource import PreviewUrlResource
-from .filepath import MediaFilePaths
-from .thumbnailer import Thumbnailer
-from .storage_provider import StorageProviderWrapper
-from .media_storage import MediaStorage
-
-from synapse.http.matrixfederationclient import MatrixFederationHttpClient
-from synapse.util.stringutils import random_string
-from synapse.api.errors import (
-    SynapseError, HttpResponseException, NotFoundError, FederationDeniedError,
-)
-
-from synapse.util.async import Linearizer
-from synapse.util.stringutils import is_ascii
-from synapse.util.logcontext import make_deferred_yieldable
-from synapse.util.retryutils import NotRetryingDestination
-
-import os
+import cgi
 import errno
+import logging
+import os
 import shutil
 
-import cgi
-import logging
-from six.moves.urllib import parse as urlparse
 from six import iteritems
+from six.moves.urllib import parse as urlparse
+
+import twisted.internet.error
+import twisted.web.http
+from twisted.internet import defer, threads
+from twisted.web.resource import Resource
+
+from synapse.api.errors import (
+    FederationDeniedError,
+    HttpResponseException,
+    NotFoundError,
+    SynapseError,
+)
+from synapse.http.matrixfederationclient import MatrixFederationHttpClient
+from synapse.util.async import Linearizer
+from synapse.util.logcontext import make_deferred_yieldable
+from synapse.util.retryutils import NotRetryingDestination
+from synapse.util.stringutils import is_ascii, random_string
+
+from ._base import FileInfo, respond_404, respond_with_responder
+from .download_resource import DownloadResource
+from .filepath import MediaFilePaths
+from .identicon_resource import IdenticonResource
+from .media_storage import MediaStorage
+from .preview_url_resource import PreviewUrlResource
+from .storage_provider import StorageProviderWrapper
+from .thumbnail_resource import ThumbnailResource
+from .thumbnailer import Thumbnailer
+from .upload_resource import UploadResource
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/rest/media/v1/media_storage.py b/synapse/rest/media/v1/media_storage.py
index d6b8ebbedb..b25993fcb5 100644
--- a/synapse/rest/media/v1/media_storage.py
+++ b/synapse/rest/media/v1/media_storage.py
@@ -13,22 +13,21 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer, threads
-from twisted.protocols.basic import FileSender
+import contextlib
+import logging
+import os
+import shutil
+import sys
 
 import six
 
-from ._base import Responder
+from twisted.internet import defer, threads
+from twisted.protocols.basic import FileSender
 
 from synapse.util.file_consumer import BackgroundFileConsumer
 from synapse.util.logcontext import make_deferred_yieldable
 
-import contextlib
-import os
-import logging
-import shutil
-import sys
-
+from ._base import Responder
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/rest/media/v1/preview_url_resource.py b/synapse/rest/media/v1/preview_url_resource.py
index adca490640..4e3a18ce08 100644
--- a/synapse/rest/media/v1/preview_url_resource.py
+++ b/synapse/rest/media/v1/preview_url_resource.py
@@ -24,31 +24,28 @@ import shutil
 import sys
 import traceback
 
+from six import string_types
+from six.moves import urllib_parse as urlparse
+
 from canonicaljson import json
 
-from six.moves import urllib_parse as urlparse
-from six import string_types
-
-from twisted.web.server import NOT_DONE_YET
 from twisted.internet import defer
 from twisted.web.resource import Resource
+from twisted.web.server import NOT_DONE_YET
 
-from ._base import FileInfo
-
-from synapse.api.errors import (
-    SynapseError, Codes,
-)
-from synapse.util.logcontext import make_deferred_yieldable, run_in_background
-from synapse.util.stringutils import random_string
-from synapse.util.caches.expiringcache import ExpiringCache
+from synapse.api.errors import Codes, SynapseError
 from synapse.http.client import SpiderHttpClient
 from synapse.http.server import (
-    respond_with_json_bytes,
     respond_with_json,
+    respond_with_json_bytes,
     wrap_json_request_handler,
 )
 from synapse.util.async import ObservableDeferred
-from synapse.util.stringutils import is_ascii
+from synapse.util.caches.expiringcache import ExpiringCache
+from synapse.util.logcontext import make_deferred_yieldable, run_in_background
+from synapse.util.stringutils import is_ascii, random_string
+
+from ._base import FileInfo
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/rest/media/v1/storage_provider.py b/synapse/rest/media/v1/storage_provider.py
index 0252afd9d3..7b9f8b4d79 100644
--- a/synapse/rest/media/v1/storage_provider.py
+++ b/synapse/rest/media/v1/storage_provider.py
@@ -13,17 +13,16 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer, threads
-
-from .media_storage import FileResponder
-
-from synapse.config._base import Config
-from synapse.util.logcontext import run_in_background
-
 import logging
 import os
 import shutil
 
+from twisted.internet import defer, threads
+
+from synapse.config._base import Config
+from synapse.util.logcontext import run_in_background
+
+from .media_storage import FileResponder
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/rest/media/v1/thumbnail_resource.py b/synapse/rest/media/v1/thumbnail_resource.py
index aae6e464e8..5305e9175f 100644
--- a/synapse/rest/media/v1/thumbnail_resource.py
+++ b/synapse/rest/media/v1/thumbnail_resource.py
@@ -20,13 +20,14 @@ from twisted.internet import defer
 from twisted.web.resource import Resource
 from twisted.web.server import NOT_DONE_YET
 
-from synapse.http.server import (
-    set_cors_headers,
-    wrap_json_request_handler,
-)
+from synapse.http.server import set_cors_headers, wrap_json_request_handler
 from synapse.http.servlet import parse_integer, parse_string
+
 from ._base import (
-    FileInfo, parse_media_id, respond_404, respond_with_file,
+    FileInfo,
+    parse_media_id,
+    respond_404,
+    respond_with_file,
     respond_with_responder,
 )
 
diff --git a/synapse/rest/media/v1/thumbnailer.py b/synapse/rest/media/v1/thumbnailer.py
index e1ee535b9a..a4b26c2587 100644
--- a/synapse/rest/media/v1/thumbnailer.py
+++ b/synapse/rest/media/v1/thumbnailer.py
@@ -13,10 +13,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import PIL.Image as Image
+import logging
 from io import BytesIO
 
-import logging
+import PIL.Image as Image
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/rest/media/v1/upload_resource.py b/synapse/rest/media/v1/upload_resource.py
index 7567476fce..1a98120e1d 100644
--- a/synapse/rest/media/v1/upload_resource.py
+++ b/synapse/rest/media/v1/upload_resource.py
@@ -20,10 +20,7 @@ from twisted.web.resource import Resource
 from twisted.web.server import NOT_DONE_YET
 
 from synapse.api.errors import SynapseError
-from synapse.http.server import (
-    respond_with_json,
-    wrap_json_request_handler,
-)
+from synapse.http.server import respond_with_json, wrap_json_request_handler
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/server.py b/synapse/server.py
index c29c19289a..92bea96c5c 100644
--- a/synapse/server.py
+++ b/synapse/server.py
@@ -33,19 +33,30 @@ from synapse.crypto.keyring import Keyring
 from synapse.events.builder import EventBuilderFactory
 from synapse.events.spamcheck import SpamChecker
 from synapse.federation.federation_client import FederationClient
-from synapse.federation.federation_server import FederationServer
+from synapse.federation.federation_server import (
+    FederationHandlerRegistry,
+    FederationServer,
+)
 from synapse.federation.send_queue import FederationRemoteSendQueue
-from synapse.federation.federation_server import FederationHandlerRegistry
-from synapse.federation.transport.client import TransportLayerClient
 from synapse.federation.transaction_queue import TransactionQueue
+from synapse.federation.transport.client import TransportLayerClient
+from synapse.groups.attestations import GroupAttestationSigning, GroupAttestionRenewer
+from synapse.groups.groups_server import GroupsServerHandler
 from synapse.handlers import Handlers
 from synapse.handlers.appservice import ApplicationServicesHandler
 from synapse.handlers.auth import AuthHandler, MacaroonGenerator
 from synapse.handlers.deactivate_account import DeactivateAccountHandler
-from synapse.handlers.devicemessage import DeviceMessageHandler
 from synapse.handlers.device import DeviceHandler
+from synapse.handlers.devicemessage import DeviceMessageHandler
 from synapse.handlers.e2e_keys import E2eKeysHandler
+from synapse.handlers.events import EventHandler, EventStreamHandler
+from synapse.handlers.groups_local import GroupsLocalHandler
+from synapse.handlers.initial_sync import InitialSyncHandler
+from synapse.handlers.message import EventCreationHandler
 from synapse.handlers.presence import PresenceHandler
+from synapse.handlers.profile import ProfileHandler
+from synapse.handlers.read_marker import ReadMarkerHandler
+from synapse.handlers.receipts import ReceiptsHandler
 from synapse.handlers.room import RoomCreationHandler
 from synapse.handlers.room_list import RoomListHandler
 from synapse.handlers.room_member import RoomMemberMasterHandler
@@ -53,17 +64,8 @@ from synapse.handlers.room_member_worker import RoomMemberWorkerHandler
 from synapse.handlers.set_password import SetPasswordHandler
 from synapse.handlers.sync import SyncHandler
 from synapse.handlers.typing import TypingHandler
-from synapse.handlers.events import EventHandler, EventStreamHandler
-from synapse.handlers.initial_sync import InitialSyncHandler
-from synapse.handlers.receipts import ReceiptsHandler
-from synapse.handlers.read_marker import ReadMarkerHandler
 from synapse.handlers.user_directory import UserDirectoryHandler
-from synapse.handlers.groups_local import GroupsLocalHandler
-from synapse.handlers.profile import ProfileHandler
-from synapse.handlers.message import EventCreationHandler
-from synapse.groups.groups_server import GroupsServerHandler
-from synapse.groups.attestations import GroupAttestionRenewer, GroupAttestationSigning
-from synapse.http.client import SimpleHttpClient, InsecureInterceptableContextFactory
+from synapse.http.client import InsecureInterceptableContextFactory, SimpleHttpClient
 from synapse.http.matrixfederationclient import MatrixFederationHttpClient
 from synapse.notifier import Notifier
 from synapse.push.action_generator import ActionGenerator
@@ -74,9 +76,7 @@ from synapse.rest.media.v1.media_repository import (
 )
 from synapse.server_notices.server_notices_manager import ServerNoticesManager
 from synapse.server_notices.server_notices_sender import ServerNoticesSender
-from synapse.server_notices.worker_server_notices_sender import (
-    WorkerServerNoticesSender,
-)
+from synapse.server_notices.worker_server_notices_sender import WorkerServerNoticesSender
 from synapse.state import StateHandler, StateResolutionHandler
 from synapse.storage import DataStore
 from synapse.streams.events import EventSources
diff --git a/synapse/server_notices/consent_server_notices.py b/synapse/server_notices/consent_server_notices.py
index bb74af1af5..5e3044d164 100644
--- a/synapse/server_notices/consent_server_notices.py
+++ b/synapse/server_notices/consent_server_notices.py
@@ -14,7 +14,8 @@
 # limitations under the License.
 import logging
 
-from six import (iteritems, string_types)
+from six import iteritems, string_types
+
 from twisted.internet import defer
 
 from synapse.api.errors import SynapseError
diff --git a/synapse/state.py b/synapse/state.py
index 8098db94b4..15a593d41c 100644
--- a/synapse/state.py
+++ b/synapse/state.py
@@ -14,25 +14,25 @@
 # limitations under the License.
 
 
+import hashlib
+import logging
+from collections import namedtuple
+
+from six import iteritems, itervalues
+
+from frozendict import frozendict
+
 from twisted.internet import defer
 
 from synapse import event_auth
-from synapse.util.logutils import log_function
-from synapse.util.caches.expiringcache import ExpiringCache
-from synapse.util.metrics import Measure
 from synapse.api.constants import EventTypes
 from synapse.api.errors import AuthError
 from synapse.events.snapshot import EventContext
 from synapse.util.async import Linearizer
 from synapse.util.caches import CACHE_SIZE_FACTOR
-
-from collections import namedtuple
-from frozendict import frozendict
-
-import logging
-import hashlib
-
-from six import iteritems, itervalues
+from synapse.util.caches.expiringcache import ExpiringCache
+from synapse.util.logutils import log_function
+from synapse.util.metrics import Measure
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/storage/__init__.py b/synapse/storage/__init__.py
index e843b702b9..ba88a54979 100644
--- a/synapse/storage/__init__.py
+++ b/synapse/storage/__init__.py
@@ -15,52 +15,49 @@
 # limitations under the License.
 
 import datetime
-from dateutil import tz
-import time
 import logging
+import time
 
-from synapse.storage.devices import DeviceStore
-from synapse.storage.user_erasure_store import UserErasureStore
-from .appservice import (
-    ApplicationServiceStore, ApplicationServiceTransactionStore
-)
-from .directory import DirectoryStore
-from .events import EventsStore
-from .presence import PresenceStore, UserPresenceState
-from .profile import ProfileStore
-from .registration import RegistrationStore
-from .room import RoomStore
-from .roommember import RoomMemberStore
-from .stream import StreamStore
-from .transactions import TransactionStore
-from .keys import KeyStore
-from .event_federation import EventFederationStore
-from .pusher import PusherStore
-from .push_rule import PushRuleStore
-from .media_repository import MediaRepositoryStore
-from .rejections import RejectionsStore
-from .event_push_actions import EventPushActionsStore
-from .deviceinbox import DeviceInboxStore
-from .group_server import GroupServerStore
-from .state import StateStore
-from .signatures import SignatureStore
-from .filtering import FilteringStore
-from .end_to_end_keys import EndToEndKeyStore
-
-from .receipts import ReceiptsStore
-from .search import SearchStore
-from .tags import TagsStore
-from .account_data import AccountDataStore
-from .openid import OpenIdStore
-from .client_ips import ClientIpStore
-from .user_directory import UserDirectoryStore
-
-from .util.id_generators import IdGenerator, StreamIdGenerator, ChainedIdGenerator
-from .engines import PostgresEngine
+from dateutil import tz
 
 from synapse.api.constants import PresenceState
+from synapse.storage.devices import DeviceStore
+from synapse.storage.user_erasure_store import UserErasureStore
 from synapse.util.caches.stream_change_cache import StreamChangeCache
 
+from .account_data import AccountDataStore
+from .appservice import ApplicationServiceStore, ApplicationServiceTransactionStore
+from .client_ips import ClientIpStore
+from .deviceinbox import DeviceInboxStore
+from .directory import DirectoryStore
+from .end_to_end_keys import EndToEndKeyStore
+from .engines import PostgresEngine
+from .event_federation import EventFederationStore
+from .event_push_actions import EventPushActionsStore
+from .events import EventsStore
+from .filtering import FilteringStore
+from .group_server import GroupServerStore
+from .keys import KeyStore
+from .media_repository import MediaRepositoryStore
+from .openid import OpenIdStore
+from .presence import PresenceStore, UserPresenceState
+from .profile import ProfileStore
+from .push_rule import PushRuleStore
+from .pusher import PusherStore
+from .receipts import ReceiptsStore
+from .registration import RegistrationStore
+from .rejections import RejectionsStore
+from .room import RoomStore
+from .roommember import RoomMemberStore
+from .search import SearchStore
+from .signatures import SignatureStore
+from .state import StateStore
+from .stream import StreamStore
+from .tags import TagsStore
+from .transactions import TransactionStore
+from .user_directory import UserDirectoryStore
+from .util.id_generators import ChainedIdGenerator, IdGenerator, StreamIdGenerator
+
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/storage/_base.py b/synapse/storage/_base.py
index 22d6257a9f..98dde77431 100644
--- a/synapse/storage/_base.py
+++ b/synapse/storage/_base.py
@@ -13,22 +13,21 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import logging
+import sys
+import threading
+import time
 
-from synapse.api.errors import StoreError
-from synapse.util.logcontext import LoggingContext, PreserveLoggingContext
-from synapse.util.caches.descriptors import Cache
-from synapse.storage.engines import PostgresEngine
+from six import iteritems, iterkeys, itervalues
+from six.moves import intern, range
 
 from prometheus_client import Histogram
 
 from twisted.internet import defer
 
-import sys
-import time
-import threading
-
-from six import itervalues, iterkeys, iteritems
-from six.moves import intern, range
+from synapse.api.errors import StoreError
+from synapse.storage.engines import PostgresEngine
+from synapse.util.caches.descriptors import Cache
+from synapse.util.logcontext import LoggingContext, PreserveLoggingContext
 
 logger = logging.getLogger(__name__)
 
@@ -221,7 +220,7 @@ class SQLBaseStore(object):
         self._clock.looping_call(loop, 10000)
 
     def _new_transaction(self, conn, desc, after_callbacks, exception_callbacks,
-                         logging_context, func, *args, **kwargs):
+                         func, *args, **kwargs):
         start = time.time()
         txn_id = self._TXN_ID
 
@@ -285,8 +284,7 @@ class SQLBaseStore(object):
             end = time.time()
             duration = end - start
 
-            if logging_context is not None:
-                logging_context.add_database_transaction(duration)
+            LoggingContext.current_context().add_database_transaction(duration)
 
             transaction_logger.debug("[TXN END] {%s} %f sec", name, duration)
 
@@ -310,19 +308,15 @@ class SQLBaseStore(object):
         Returns:
             Deferred: The result of func
         """
-        current_context = LoggingContext.current_context()
-
         after_callbacks = []
         exception_callbacks = []
 
-        def inner_func(conn, *args, **kwargs):
-            return self._new_transaction(
-                conn, desc, after_callbacks, exception_callbacks, current_context,
-                func, *args, **kwargs
-            )
-
         try:
-            result = yield self.runWithConnection(inner_func, *args, **kwargs)
+            result = yield self.runWithConnection(
+                self._new_transaction,
+                desc, after_callbacks, exception_callbacks, func,
+                *args, **kwargs
+            )
 
             for after_callback, after_args, after_kwargs in after_callbacks:
                 after_callback(*after_args, **after_kwargs)
@@ -347,22 +341,25 @@ class SQLBaseStore(object):
         Returns:
             Deferred: The result of func
         """
-        current_context = LoggingContext.current_context()
+        parent_context = LoggingContext.current_context()
+        if parent_context == LoggingContext.sentinel:
+            logger.warn(
+                "Running db txn from sentinel context: metrics will be lost",
+            )
+            parent_context = None
 
         start_time = time.time()
 
         def inner_func(conn, *args, **kwargs):
-            with LoggingContext("runWithConnection") as context:
+            with LoggingContext("runWithConnection", parent_context) as context:
                 sched_duration_sec = time.time() - start_time
                 sql_scheduling_timer.observe(sched_duration_sec)
-                current_context.add_database_scheduled(sched_duration_sec)
+                context.add_database_scheduled(sched_duration_sec)
 
                 if self.database_engine.is_connection_closed(conn):
                     logger.debug("Reconnecting closed database connection")
                     conn.reconnect()
 
-                current_context.copy_to(context)
-
                 return func(conn, *args, **kwargs)
 
         with PreserveLoggingContext():
diff --git a/synapse/storage/account_data.py b/synapse/storage/account_data.py
index 7034a61399..bbc3355c73 100644
--- a/synapse/storage/account_data.py
+++ b/synapse/storage/account_data.py
@@ -14,18 +14,17 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import abc
+import logging
+
+from canonicaljson import json
+
 from twisted.internet import defer
 
 from synapse.storage._base import SQLBaseStore
 from synapse.storage.util.id_generators import StreamIdGenerator
-
-from synapse.util.caches.stream_change_cache import StreamChangeCache
 from synapse.util.caches.descriptors import cached, cachedInlineCallbacks
-
-from canonicaljson import json
-
-import abc
-import logging
+from synapse.util.caches.stream_change_cache import StreamChangeCache
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/storage/appservice.py b/synapse/storage/appservice.py
index 4d32d0bdf6..9f12b360bc 100644
--- a/synapse/storage/appservice.py
+++ b/synapse/storage/appservice.py
@@ -15,14 +15,16 @@
 # limitations under the License.
 import logging
 import re
-from twisted.internet import defer
+
 from canonicaljson import json
 
+from twisted.internet import defer
+
 from synapse.appservice import AppServiceTransaction
 from synapse.config.appservice import load_appservices
 from synapse.storage.events import EventsWorkerStore
-from ._base import SQLBaseStore
 
+from ._base import SQLBaseStore
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/storage/background_updates.py b/synapse/storage/background_updates.py
index af18964510..dc9eca7d15 100644
--- a/synapse/storage/background_updates.py
+++ b/synapse/storage/background_updates.py
@@ -13,14 +13,14 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import SQLBaseStore
-from . import engines
-
-from twisted.internet import defer
+import logging
 
 from canonicaljson import json
 
-import logging
+from twisted.internet import defer
+
+from . import engines
+from ._base import SQLBaseStore
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/storage/client_ips.py b/synapse/storage/client_ips.py
index 30d3541cf7..87c4e54931 100644
--- a/synapse/storage/client_ips.py
+++ b/synapse/storage/client_ips.py
@@ -15,15 +15,14 @@
 
 import logging
 
-from twisted.internet import defer
+from six import iteritems
 
-from ._base import Cache
-from . import background_updates
+from twisted.internet import defer
 
 from synapse.util.caches import CACHE_SIZE_FACTOR
 
-from six import iteritems
-
+from . import background_updates
+from ._base import Cache
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/storage/deviceinbox.py b/synapse/storage/deviceinbox.py
index 38addbf9c0..73646da025 100644
--- a/synapse/storage/deviceinbox.py
+++ b/synapse/storage/deviceinbox.py
@@ -19,10 +19,9 @@ from canonicaljson import json
 
 from twisted.internet import defer
 
-from .background_updates import BackgroundUpdateStore
-
 from synapse.util.caches.expiringcache import ExpiringCache
 
+from .background_updates import BackgroundUpdateStore
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/storage/devices.py b/synapse/storage/devices.py
index 2ed9ada783..ec68e39f1e 100644
--- a/synapse/storage/devices.py
+++ b/synapse/storage/devices.py
@@ -14,15 +14,16 @@
 # limitations under the License.
 import logging
 
-from twisted.internet import defer
-
-from synapse.api.errors import StoreError
-from ._base import SQLBaseStore, Cache
-from synapse.util.caches.descriptors import cached, cachedList, cachedInlineCallbacks
+from six import iteritems, itervalues
 
 from canonicaljson import json
 
-from six import itervalues, iteritems
+from twisted.internet import defer
+
+from synapse.api.errors import StoreError
+from synapse.util.caches.descriptors import cached, cachedInlineCallbacks, cachedList
+
+from ._base import Cache, SQLBaseStore
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/storage/directory.py b/synapse/storage/directory.py
index d0c0059757..808194236a 100644
--- a/synapse/storage/directory.py
+++ b/synapse/storage/directory.py
@@ -13,15 +13,14 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import SQLBaseStore
-from synapse.util.caches.descriptors import cached
-
-from synapse.api.errors import SynapseError
+from collections import namedtuple
 
 from twisted.internet import defer
 
-from collections import namedtuple
+from synapse.api.errors import SynapseError
+from synapse.util.caches.descriptors import cached
 
+from ._base import SQLBaseStore
 
 RoomAliasMapping = namedtuple(
     "RoomAliasMapping",
diff --git a/synapse/storage/end_to_end_keys.py b/synapse/storage/end_to_end_keys.py
index 181047c8b7..7ae5c65482 100644
--- a/synapse/storage/end_to_end_keys.py
+++ b/synapse/storage/end_to_end_keys.py
@@ -12,16 +12,16 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+from six import iteritems
+
+from canonicaljson import encode_canonical_json, json
+
 from twisted.internet import defer
 
 from synapse.util.caches.descriptors import cached
 
-from canonicaljson import encode_canonical_json, json
-
 from ._base import SQLBaseStore
 
-from six import iteritems
-
 
 class EndToEndKeyStore(SQLBaseStore):
     def set_e2e_device_keys(self, user_id, device_id, time_now, device_keys):
diff --git a/synapse/storage/engines/__init__.py b/synapse/storage/engines/__init__.py
index 8c868ece75..e2f9de8451 100644
--- a/synapse/storage/engines/__init__.py
+++ b/synapse/storage/engines/__init__.py
@@ -13,13 +13,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import IncorrectDatabaseSetup
-from .postgres import PostgresEngine
-from .sqlite3 import Sqlite3Engine
-
 import importlib
 import platform
 
+from ._base import IncorrectDatabaseSetup
+from .postgres import PostgresEngine
+from .sqlite3 import Sqlite3Engine
 
 SUPPORTED_MODULE = {
     "sqlite3": Sqlite3Engine,
diff --git a/synapse/storage/engines/sqlite3.py b/synapse/storage/engines/sqlite3.py
index 60f0fa7fb3..19949fc474 100644
--- a/synapse/storage/engines/sqlite3.py
+++ b/synapse/storage/engines/sqlite3.py
@@ -13,11 +13,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.storage.prepare_database import prepare_database
-
 import struct
 import threading
 
+from synapse.storage.prepare_database import prepare_database
+
 
 class Sqlite3Engine(object):
     single_threaded = True
diff --git a/synapse/storage/event_federation.py b/synapse/storage/event_federation.py
index 8fbf7ffba7..8d366d1b91 100644
--- a/synapse/storage/event_federation.py
+++ b/synapse/storage/event_federation.py
@@ -12,23 +12,21 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+import logging
 import random
 
+from six.moves import range
+from six.moves.queue import Empty, PriorityQueue
+
+from unpaddedbase64 import encode_base64
+
 from twisted.internet import defer
 
+from synapse.api.errors import StoreError
 from synapse.storage._base import SQLBaseStore
 from synapse.storage.events import EventsWorkerStore
 from synapse.storage.signatures import SignatureWorkerStore
-
-from synapse.api.errors import StoreError
 from synapse.util.caches.descriptors import cached
-from unpaddedbase64 import encode_base64
-
-import logging
-from six.moves.queue import PriorityQueue, Empty
-
-from six.moves import range
-
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/storage/event_push_actions.py b/synapse/storage/event_push_actions.py
index 05cb3f61ce..29b511ae5e 100644
--- a/synapse/storage/event_push_actions.py
+++ b/synapse/storage/event_push_actions.py
@@ -14,15 +14,16 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.storage._base import SQLBaseStore, LoggingTransaction
-from twisted.internet import defer
-from synapse.util.caches.descriptors import cachedInlineCallbacks
-
 import logging
 
+from six import iteritems
+
 from canonicaljson import json
 
-from six import iteritems
+from twisted.internet import defer
+
+from synapse.storage._base import LoggingTransaction, SQLBaseStore
+from synapse.util.caches.descriptors import cachedInlineCallbacks
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/storage/events.py b/synapse/storage/events.py
index a54abb9edd..2aaab0d02c 100644
--- a/synapse/storage/events.py
+++ b/synapse/storage/events.py
@@ -14,37 +14,33 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from collections import OrderedDict, deque, namedtuple
-from functools import wraps
 import itertools
 import logging
+from collections import OrderedDict, deque, namedtuple
+from functools import wraps
+
+from six import iteritems, itervalues
+from six.moves import range
 
 from canonicaljson import json
+from prometheus_client import Counter
 
 from twisted.internet import defer
 
-from synapse.storage.events_worker import EventsWorkerStore
-from synapse.util.async import ObservableDeferred
-from synapse.util.frozenutils import frozendict_json_encoder
-from synapse.util.logcontext import (
-    PreserveLoggingContext, make_deferred_yieldable,
-)
-from synapse.util.logutils import log_function
-from synapse.util.metrics import Measure
+import synapse.metrics
 from synapse.api.constants import EventTypes
 from synapse.api.errors import SynapseError
-from synapse.util.caches.descriptors import cached, cachedInlineCallbacks
-from synapse.types import get_domain_from_id, RoomStreamToken
-import synapse.metrics
-
 # these are only included to make the type annotations work
-from synapse.events import EventBase    # noqa: F401
-from synapse.events.snapshot import EventContext   # noqa: F401
-
-from six.moves import range
-from six import itervalues, iteritems
-
-from prometheus_client import Counter
+from synapse.events import EventBase  # noqa: F401
+from synapse.events.snapshot import EventContext  # noqa: F401
+from synapse.storage.events_worker import EventsWorkerStore
+from synapse.types import RoomStreamToken, get_domain_from_id
+from synapse.util.async import ObservableDeferred
+from synapse.util.caches.descriptors import cached, cachedInlineCallbacks
+from synapse.util.frozenutils import frozendict_json_encoder
+from synapse.util.logcontext import PreserveLoggingContext, make_deferred_yieldable
+from synapse.util.logutils import log_function
+from synapse.util.metrics import Measure
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/storage/events_worker.py b/synapse/storage/events_worker.py
index 896225aab9..67433606c6 100644
--- a/synapse/storage/events_worker.py
+++ b/synapse/storage/events_worker.py
@@ -12,29 +12,28 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-from ._base import SQLBaseStore
-
-from twisted.internet import defer
-
-from synapse.events import FrozenEvent
-from synapse.events.utils import prune_event
-
-from synapse.util.logcontext import (
-    PreserveLoggingContext, make_deferred_yieldable, run_in_background,
-    LoggingContext,
-)
-from synapse.util.metrics import Measure
-from synapse.api.errors import SynapseError
-
-from collections import namedtuple
-
 import logging
+from collections import namedtuple
 
 from canonicaljson import json
 
+from twisted.internet import defer
+
+from synapse.api.errors import SynapseError
 # these are only included to make the type annotations work
-from synapse.events import EventBase    # noqa: F401
-from synapse.events.snapshot import EventContext   # noqa: F401
+from synapse.events import EventBase  # noqa: F401
+from synapse.events import FrozenEvent
+from synapse.events.snapshot import EventContext  # noqa: F401
+from synapse.events.utils import prune_event
+from synapse.util.logcontext import (
+    LoggingContext,
+    PreserveLoggingContext,
+    make_deferred_yieldable,
+    run_in_background,
+)
+from synapse.util.metrics import Measure
+
+from ._base import SQLBaseStore
 
 logger = logging.getLogger(__name__)
 
@@ -223,32 +222,47 @@ class EventsWorkerStore(SQLBaseStore):
         """Takes a database connection and waits for requests for events from
         the _event_fetch_list queue.
         """
-        event_list = []
         i = 0
         while True:
+            with self._event_fetch_lock:
+                event_list = self._event_fetch_list
+                self._event_fetch_list = []
+
+                if not event_list:
+                    single_threaded = self.database_engine.single_threaded
+                    if single_threaded or i > EVENT_QUEUE_ITERATIONS:
+                        self._event_fetch_ongoing -= 1
+                        return
+                    else:
+                        self._event_fetch_lock.wait(EVENT_QUEUE_TIMEOUT_S)
+                        i += 1
+                        continue
+                i = 0
+
+            self._fetch_event_list(conn, event_list)
+
+    def _fetch_event_list(self, conn, event_list):
+        """Handle a load of requests from the _event_fetch_list queue
+
+        Args:
+            conn (twisted.enterprise.adbapi.Connection): database connection
+
+            event_list (list[Tuple[list[str], Deferred]]):
+                The fetch requests. Each entry consists of a list of event
+                ids to be fetched, and a deferred to be completed once the
+                events have been fetched.
+
+        """
+        with Measure(self._clock, "_fetch_event_list"):
             try:
-                with self._event_fetch_lock:
-                    event_list = self._event_fetch_list
-                    self._event_fetch_list = []
-
-                    if not event_list:
-                        single_threaded = self.database_engine.single_threaded
-                        if single_threaded or i > EVENT_QUEUE_ITERATIONS:
-                            self._event_fetch_ongoing -= 1
-                            return
-                        else:
-                            self._event_fetch_lock.wait(EVENT_QUEUE_TIMEOUT_S)
-                            i += 1
-                            continue
-                    i = 0
-
                 event_id_lists = zip(*event_list)[0]
                 event_ids = [
                     item for sublist in event_id_lists for item in sublist
                 ]
 
                 rows = self._new_transaction(
-                    conn, "do_fetch", [], [], None, self._fetch_event_rows, event_ids
+                    conn, "do_fetch", [], [],
+                    self._fetch_event_rows, event_ids,
                 )
 
                 row_dict = {
@@ -281,9 +295,8 @@ class EventsWorkerStore(SQLBaseStore):
                             with PreserveLoggingContext():
                                 d.errback(e)
 
-                if event_list:
-                    with PreserveLoggingContext():
-                        self.hs.get_reactor().callFromThread(fire, event_list)
+                with PreserveLoggingContext():
+                    self.hs.get_reactor().callFromThread(fire, event_list)
 
     @defer.inlineCallbacks
     def _enqueue_events(self, events, check_redacted=True, allow_rejected=False):
diff --git a/synapse/storage/filtering.py b/synapse/storage/filtering.py
index eae6027cee..2d5896c5b4 100644
--- a/synapse/storage/filtering.py
+++ b/synapse/storage/filtering.py
@@ -13,13 +13,14 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from canonicaljson import encode_canonical_json, json
+
 from twisted.internet import defer
 
-from ._base import SQLBaseStore
-from synapse.api.errors import SynapseError, Codes
+from synapse.api.errors import Codes, SynapseError
 from synapse.util.caches.descriptors import cachedInlineCallbacks
 
-from canonicaljson import encode_canonical_json, json
+from ._base import SQLBaseStore
 
 
 class FilteringStore(SQLBaseStore):
diff --git a/synapse/storage/group_server.py b/synapse/storage/group_server.py
index b77402d295..592d1b4c2a 100644
--- a/synapse/storage/group_server.py
+++ b/synapse/storage/group_server.py
@@ -14,15 +14,14 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from canonicaljson import json
+
 from twisted.internet import defer
 
 from synapse.api.errors import SynapseError
 
 from ._base import SQLBaseStore
 
-from canonicaljson import json
-
-
 # The category ID for the "default" category. We don't store as null in the
 # database to avoid the fun of null != null
 _DEFAULT_CATEGORY_ID = ""
diff --git a/synapse/storage/keys.py b/synapse/storage/keys.py
index 0f13b61da8..f547977600 100644
--- a/synapse/storage/keys.py
+++ b/synapse/storage/keys.py
@@ -13,17 +13,19 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import SQLBaseStore
-from synapse.util.caches.descriptors import cachedInlineCallbacks
+import hashlib
+import logging
 
-from twisted.internet import defer
 import six
 
-import OpenSSL
 from signedjson.key import decode_verify_key_bytes
-import hashlib
 
-import logging
+import OpenSSL
+from twisted.internet import defer
+
+from synapse.util.caches.descriptors import cachedInlineCallbacks
+
+from ._base import SQLBaseStore
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/storage/prepare_database.py b/synapse/storage/prepare_database.py
index cf2aae0468..b290f834b3 100644
--- a/synapse/storage/prepare_database.py
+++ b/synapse/storage/prepare_database.py
@@ -20,7 +20,6 @@ import logging
 import os
 import re
 
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/storage/presence.py b/synapse/storage/presence.py
index f05d91cc58..a0c7a0dc87 100644
--- a/synapse/storage/presence.py
+++ b/synapse/storage/presence.py
@@ -13,14 +13,16 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import SQLBaseStore
-from synapse.api.constants import PresenceState
-from synapse.util.caches.descriptors import cached, cachedInlineCallbacks, cachedList
-from synapse.util import batch_iter
-
 from collections import namedtuple
+
 from twisted.internet import defer
 
+from synapse.api.constants import PresenceState
+from synapse.util import batch_iter
+from synapse.util.caches.descriptors import cached, cachedInlineCallbacks, cachedList
+
+from ._base import SQLBaseStore
+
 
 class UserPresenceState(namedtuple("UserPresenceState",
                         ("user_id", "state", "last_active_ts",
diff --git a/synapse/storage/profile.py b/synapse/storage/profile.py
index 8612bd5ecc..60295da254 100644
--- a/synapse/storage/profile.py
+++ b/synapse/storage/profile.py
@@ -15,8 +15,8 @@
 
 from twisted.internet import defer
 
-from synapse.storage.roommember import ProfileInfo
 from synapse.api.errors import StoreError
+from synapse.storage.roommember import ProfileInfo
 
 from ._base import SQLBaseStore
 
diff --git a/synapse/storage/push_rule.py b/synapse/storage/push_rule.py
index 9e52e992b3..be655d287b 100644
--- a/synapse/storage/push_rule.py
+++ b/synapse/storage/push_rule.py
@@ -14,21 +14,23 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import SQLBaseStore
+import abc
+import logging
+
+from canonicaljson import json
+
+from twisted.internet import defer
+
+from synapse.api.constants import EventTypes
+from synapse.push.baserules import list_with_base_rules
 from synapse.storage.appservice import ApplicationServiceWorkerStore
 from synapse.storage.pusher import PusherWorkerStore
 from synapse.storage.receipts import ReceiptsWorkerStore
 from synapse.storage.roommember import RoomMemberWorkerStore
 from synapse.util.caches.descriptors import cachedInlineCallbacks, cachedList
 from synapse.util.caches.stream_change_cache import StreamChangeCache
-from synapse.push.baserules import list_with_base_rules
-from synapse.api.constants import EventTypes
-from twisted.internet import defer
 
-from canonicaljson import json
-
-import abc
-import logging
+from ._base import SQLBaseStore
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/storage/pusher.py b/synapse/storage/pusher.py
index c6def861cf..cc273a57b2 100644
--- a/synapse/storage/pusher.py
+++ b/synapse/storage/pusher.py
@@ -14,15 +14,16 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import SQLBaseStore
-from twisted.internet import defer
+import logging
+import types
 
 from canonicaljson import encode_canonical_json, json
 
+from twisted.internet import defer
+
 from synapse.util.caches.descriptors import cachedInlineCallbacks, cachedList
 
-import logging
-import types
+from ._base import SQLBaseStore
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/storage/receipts.py b/synapse/storage/receipts.py
index f230a3bab7..3738901ea4 100644
--- a/synapse/storage/receipts.py
+++ b/synapse/storage/receipts.py
@@ -14,18 +14,18 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import SQLBaseStore
-from .util.id_generators import StreamIdGenerator
-from synapse.util.caches.descriptors import cachedInlineCallbacks, cachedList, cached
-from synapse.util.caches.stream_change_cache import StreamChangeCache
-
-from twisted.internet import defer
-
-from canonicaljson import json
-
 import abc
 import logging
 
+from canonicaljson import json
+
+from twisted.internet import defer
+
+from synapse.util.caches.descriptors import cached, cachedInlineCallbacks, cachedList
+from synapse.util.caches.stream_change_cache import StreamChangeCache
+
+from ._base import SQLBaseStore
+from .util.id_generators import StreamIdGenerator
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/storage/registration.py b/synapse/storage/registration.py
index 0d18f6d869..07333f777d 100644
--- a/synapse/storage/registration.py
+++ b/synapse/storage/registration.py
@@ -15,15 +15,15 @@
 
 import re
 
+from six.moves import range
+
 from twisted.internet import defer
 
-from synapse.api.errors import StoreError, Codes
+from synapse.api.errors import Codes, StoreError
 from synapse.storage import background_updates
 from synapse.storage._base import SQLBaseStore
 from synapse.util.caches.descriptors import cached, cachedInlineCallbacks
 
-from six.moves import range
-
 
 class RegistrationWorkerStore(SQLBaseStore):
     @cached()
diff --git a/synapse/storage/rejections.py b/synapse/storage/rejections.py
index 40acb5c4ed..880f047adb 100644
--- a/synapse/storage/rejections.py
+++ b/synapse/storage/rejections.py
@@ -13,10 +13,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import SQLBaseStore
-
 import logging
 
+from ._base import SQLBaseStore
+
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/storage/room.py b/synapse/storage/room.py
index ca0eb187e5..3147fb6827 100644
--- a/synapse/storage/room.py
+++ b/synapse/storage/room.py
@@ -13,6 +13,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import collections
+import logging
+import re
+
+from canonicaljson import json
+
 from twisted.internet import defer
 
 from synapse.api.errors import StoreError
@@ -20,12 +26,6 @@ from synapse.storage._base import SQLBaseStore
 from synapse.storage.search import SearchStore
 from synapse.util.caches.descriptors import cached, cachedInlineCallbacks
 
-from canonicaljson import json
-
-import collections
-import logging
-import re
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/storage/roommember.py b/synapse/storage/roommember.py
index d214e920d8..584acd618a 100644
--- a/synapse/storage/roommember.py
+++ b/synapse/storage/roommember.py
@@ -14,24 +14,23 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer
-
+import logging
 from collections import namedtuple
 
+from six import iteritems, itervalues
+
+from canonicaljson import json
+
+from twisted.internet import defer
+
+from synapse.api.constants import EventTypes, Membership
 from synapse.storage.events import EventsWorkerStore
+from synapse.types import get_domain_from_id
 from synapse.util.async import Linearizer
 from synapse.util.caches import intern_string
 from synapse.util.caches.descriptors import cached, cachedInlineCallbacks
 from synapse.util.stringutils import to_ascii
 
-from synapse.api.constants import Membership, EventTypes
-from synapse.types import get_domain_from_id
-
-import logging
-from canonicaljson import json
-
-from six import itervalues, iteritems
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/storage/schema/delta/25/fts.py b/synapse/storage/schema/delta/25/fts.py
index e7351c3ae6..4b2ffd35fd 100644
--- a/synapse/storage/schema/delta/25/fts.py
+++ b/synapse/storage/schema/delta/25/fts.py
@@ -14,11 +14,11 @@
 
 import logging
 
-from synapse.storage.prepare_database import get_statements
-from synapse.storage.engines import PostgresEngine, Sqlite3Engine
-
 import simplejson
 
+from synapse.storage.engines import PostgresEngine, Sqlite3Engine
+from synapse.storage.prepare_database import get_statements
+
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/storage/schema/delta/27/ts.py b/synapse/storage/schema/delta/27/ts.py
index 6df57b5206..414f9f5aa0 100644
--- a/synapse/storage/schema/delta/27/ts.py
+++ b/synapse/storage/schema/delta/27/ts.py
@@ -14,10 +14,10 @@
 
 import logging
 
-from synapse.storage.prepare_database import get_statements
-
 import simplejson
 
+from synapse.storage.prepare_database import get_statements
+
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/storage/schema/delta/30/as_users.py b/synapse/storage/schema/delta/30/as_users.py
index 85bd1a2006..ef7ec34346 100644
--- a/synapse/storage/schema/delta/30/as_users.py
+++ b/synapse/storage/schema/delta/30/as_users.py
@@ -12,10 +12,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import logging
-from synapse.config.appservice import load_appservices
 
 from six.moves import range
 
+from synapse.config.appservice import load_appservices
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/storage/schema/delta/31/search_update.py b/synapse/storage/schema/delta/31/search_update.py
index fe6b7d196d..7d8ca5f93f 100644
--- a/synapse/storage/schema/delta/31/search_update.py
+++ b/synapse/storage/schema/delta/31/search_update.py
@@ -12,12 +12,13 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import logging
+
+import simplejson
+
 from synapse.storage.engines import PostgresEngine
 from synapse.storage.prepare_database import get_statements
 
-import logging
-import simplejson
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/storage/schema/delta/33/event_fields.py b/synapse/storage/schema/delta/33/event_fields.py
index 1e002f9db2..bff1256a7b 100644
--- a/synapse/storage/schema/delta/33/event_fields.py
+++ b/synapse/storage/schema/delta/33/event_fields.py
@@ -12,11 +12,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.storage.prepare_database import get_statements
-
 import logging
+
 import simplejson
 
+from synapse.storage.prepare_database import get_statements
+
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/storage/schema/delta/33/remote_media_ts.py b/synapse/storage/schema/delta/33/remote_media_ts.py
index 55ae43f395..9754d3ccfb 100644
--- a/synapse/storage/schema/delta/33/remote_media_ts.py
+++ b/synapse/storage/schema/delta/33/remote_media_ts.py
@@ -14,7 +14,6 @@
 
 import time
 
-
 ALTER_TABLE = "ALTER TABLE remote_media_cache ADD COLUMN last_access_ts BIGINT"
 
 
diff --git a/synapse/storage/schema/delta/34/cache_stream.py b/synapse/storage/schema/delta/34/cache_stream.py
index 3b63a1562d..cf09e43e2b 100644
--- a/synapse/storage/schema/delta/34/cache_stream.py
+++ b/synapse/storage/schema/delta/34/cache_stream.py
@@ -12,11 +12,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.storage.prepare_database import get_statements
-from synapse.storage.engines import PostgresEngine
-
 import logging
 
+from synapse.storage.engines import PostgresEngine
+from synapse.storage.prepare_database import get_statements
+
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/storage/schema/delta/34/received_txn_purge.py b/synapse/storage/schema/delta/34/received_txn_purge.py
index 033144341c..67d505e68b 100644
--- a/synapse/storage/schema/delta/34/received_txn_purge.py
+++ b/synapse/storage/schema/delta/34/received_txn_purge.py
@@ -12,10 +12,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.storage.engines import PostgresEngine
-
 import logging
 
+from synapse.storage.engines import PostgresEngine
+
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/storage/schema/delta/34/sent_txn_purge.py b/synapse/storage/schema/delta/34/sent_txn_purge.py
index 81948e3431..0ffab10b6f 100644
--- a/synapse/storage/schema/delta/34/sent_txn_purge.py
+++ b/synapse/storage/schema/delta/34/sent_txn_purge.py
@@ -12,10 +12,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.storage.engines import PostgresEngine
-
 import logging
 
+from synapse.storage.engines import PostgresEngine
+
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/storage/schema/delta/37/remove_auth_idx.py b/synapse/storage/schema/delta/37/remove_auth_idx.py
index 20ad8bd5a6..a377884169 100644
--- a/synapse/storage/schema/delta/37/remove_auth_idx.py
+++ b/synapse/storage/schema/delta/37/remove_auth_idx.py
@@ -12,11 +12,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.storage.prepare_database import get_statements
-from synapse.storage.engines import PostgresEngine
-
 import logging
 
+from synapse.storage.engines import PostgresEngine
+from synapse.storage.prepare_database import get_statements
+
 logger = logging.getLogger(__name__)
 
 DROP_INDICES = """
diff --git a/synapse/storage/schema/delta/42/user_dir.py b/synapse/storage/schema/delta/42/user_dir.py
index ea6a18196d..506f326f4d 100644
--- a/synapse/storage/schema/delta/42/user_dir.py
+++ b/synapse/storage/schema/delta/42/user_dir.py
@@ -14,8 +14,8 @@
 
 import logging
 
-from synapse.storage.prepare_database import get_statements
 from synapse.storage.engines import PostgresEngine, Sqlite3Engine
+from synapse.storage.prepare_database import get_statements
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/storage/search.py b/synapse/storage/search.py
index 9e88d141f8..a35291a3f6 100644
--- a/synapse/storage/search.py
+++ b/synapse/storage/search.py
@@ -13,19 +13,21 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from collections import namedtuple
 import logging
 import re
-from canonicaljson import json
+from collections import namedtuple
 
 from six import string_types
 
+from canonicaljson import json
+
 from twisted.internet import defer
 
-from .background_updates import BackgroundUpdateStore
 from synapse.api.errors import SynapseError
 from synapse.storage.engines import PostgresEngine, Sqlite3Engine
 
+from .background_updates import BackgroundUpdateStore
+
 logger = logging.getLogger(__name__)
 
 SearchEntry = namedtuple('SearchEntry', [
diff --git a/synapse/storage/signatures.py b/synapse/storage/signatures.py
index 25922e5a9c..470212aa2a 100644
--- a/synapse/storage/signatures.py
+++ b/synapse/storage/signatures.py
@@ -13,15 +13,17 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer
 import six
 
-from ._base import SQLBaseStore
-
 from unpaddedbase64 import encode_base64
+
+from twisted.internet import defer
+
 from synapse.crypto.event_signing import compute_event_reference_hash
 from synapse.util.caches.descriptors import cached, cachedList
 
+from ._base import SQLBaseStore
+
 # py2 sqlite has buffer hardcoded as only binary type, so we must use it,
 # despite being deprecated and removed in favor of memoryview
 if six.PY2:
diff --git a/synapse/storage/state.py b/synapse/storage/state.py
index cd9821c270..89a05c4618 100644
--- a/synapse/storage/state.py
+++ b/synapse/storage/state.py
@@ -13,8 +13,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from collections import namedtuple
 import logging
+from collections import namedtuple
 
 from six import iteritems, itervalues
 from six.moves import range
@@ -23,10 +23,11 @@ from twisted.internet import defer
 
 from synapse.storage.background_updates import BackgroundUpdateStore
 from synapse.storage.engines import PostgresEngine
-from synapse.util.caches import intern_string, get_cache_factor_for
+from synapse.util.caches import get_cache_factor_for, intern_string
 from synapse.util.caches.descriptors import cached, cachedList
 from synapse.util.caches.dictionary_cache import DictionaryCache
 from synapse.util.stringutils import to_ascii
+
 from ._base import SQLBaseStore
 
 logger = logging.getLogger(__name__)
diff --git a/synapse/storage/stream.py b/synapse/storage/stream.py
index fb463c525a..66856342f0 100644
--- a/synapse/storage/stream.py
+++ b/synapse/storage/stream.py
@@ -33,22 +33,20 @@ what sort order was used:
       and stream ordering columns respectively.
 """
 
+import abc
+import logging
+from collections import namedtuple
+
+from six.moves import range
+
 from twisted.internet import defer
 
 from synapse.storage._base import SQLBaseStore
+from synapse.storage.engines import PostgresEngine
 from synapse.storage.events import EventsWorkerStore
-
 from synapse.types import RoomStreamToken
 from synapse.util.caches.stream_change_cache import StreamChangeCache
 from synapse.util.logcontext import make_deferred_yieldable, run_in_background
-from synapse.storage.engines import PostgresEngine
-
-import abc
-import logging
-
-from six.moves import range
-from collections import namedtuple
-
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/storage/tags.py b/synapse/storage/tags.py
index 04d123ed95..0f657b2bd3 100644
--- a/synapse/storage/tags.py
+++ b/synapse/storage/tags.py
@@ -14,17 +14,17 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.storage.account_data import AccountDataWorkerStore
-
-from synapse.util.caches.descriptors import cached
-from twisted.internet import defer
-
-from canonicaljson import json
-
 import logging
 
 from six.moves import range
 
+from canonicaljson import json
+
+from twisted.internet import defer
+
+from synapse.storage.account_data import AccountDataWorkerStore
+from synapse.util.caches.descriptors import cached
+
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/storage/transactions.py b/synapse/storage/transactions.py
index acbc03446e..c3bc94f56d 100644
--- a/synapse/storage/transactions.py
+++ b/synapse/storage/transactions.py
@@ -13,17 +13,18 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import SQLBaseStore
-from synapse.util.caches.descriptors import cached
+import logging
+from collections import namedtuple
 
-from twisted.internet import defer
 import six
 
 from canonicaljson import encode_canonical_json, json
 
-from collections import namedtuple
+from twisted.internet import defer
 
-import logging
+from synapse.util.caches.descriptors import cached
+
+from ._base import SQLBaseStore
 
 # py2 sqlite has buffer hardcoded as only binary type, so we must use it,
 # despite being deprecated and removed in favor of memoryview
diff --git a/synapse/storage/user_directory.py b/synapse/storage/user_directory.py
index 275c299998..a8781b0e5d 100644
--- a/synapse/storage/user_directory.py
+++ b/synapse/storage/user_directory.py
@@ -13,19 +13,19 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer
-
-from ._base import SQLBaseStore
-
-from synapse.util.caches.descriptors import cached, cachedInlineCallbacks
-from synapse.api.constants import EventTypes, JoinRules
-from synapse.storage.engines import PostgresEngine, Sqlite3Engine
-from synapse.types import get_domain_from_id, get_localpart_from_id
+import logging
+import re
 
 from six import iteritems
 
-import re
-import logging
+from twisted.internet import defer
+
+from synapse.api.constants import EventTypes, JoinRules
+from synapse.storage.engines import PostgresEngine, Sqlite3Engine
+from synapse.types import get_domain_from_id, get_localpart_from_id
+from synapse.util.caches.descriptors import cached, cachedInlineCallbacks
+
+from ._base import SQLBaseStore
 
 logger = logging.getLogger(__name__)
 
@@ -265,7 +265,7 @@ class UserDirectoryStore(SQLBaseStore):
         self.get_user_in_public_room.invalidate((user_id,))
 
     def get_users_in_public_due_to_room(self, room_id):
-        """Get all user_ids that are in the room directory becuase they're
+        """Get all user_ids that are in the room directory because they're
         in the given room_id
         """
         return self._simple_select_onecol(
@@ -277,7 +277,7 @@ class UserDirectoryStore(SQLBaseStore):
 
     @defer.inlineCallbacks
     def get_users_in_dir_due_to_room(self, room_id):
-        """Get all user_ids that are in the room directory becuase they're
+        """Get all user_ids that are in the room directory because they're
         in the given room_id
         """
         user_ids_dir = yield self._simple_select_onecol(
diff --git a/synapse/storage/user_erasure_store.py b/synapse/storage/user_erasure_store.py
index 47bfc01e84..be013f4427 100644
--- a/synapse/storage/user_erasure_store.py
+++ b/synapse/storage/user_erasure_store.py
@@ -17,7 +17,7 @@ import operator
 from twisted.internet import defer
 
 from synapse.storage._base import SQLBaseStore
-from synapse.util.caches.descriptors import cachedList, cached
+from synapse.util.caches.descriptors import cached, cachedList
 
 
 class UserErasureWorkerStore(SQLBaseStore):
diff --git a/synapse/storage/util/id_generators.py b/synapse/storage/util/id_generators.py
index 95031dc9ec..d6160d5e4d 100644
--- a/synapse/storage/util/id_generators.py
+++ b/synapse/storage/util/id_generators.py
@@ -13,9 +13,9 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from collections import deque
 import contextlib
 import threading
+from collections import deque
 
 
 class IdGenerator(object):
diff --git a/synapse/streams/config.py b/synapse/streams/config.py
index ca78e551cb..46ccbbda7d 100644
--- a/synapse/streams/config.py
+++ b/synapse/streams/config.py
@@ -13,11 +13,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.api.errors import SynapseError
-from synapse.types import StreamToken
-
 import logging
 
+from synapse.api.errors import SynapseError
+from synapse.types import StreamToken
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/streams/events.py b/synapse/streams/events.py
index f03ad99118..e5220132a3 100644
--- a/synapse/streams/events.py
+++ b/synapse/streams/events.py
@@ -15,13 +15,12 @@
 
 from twisted.internet import defer
 
-from synapse.types import StreamToken
-
+from synapse.handlers.account_data import AccountDataEventSource
 from synapse.handlers.presence import PresenceEventSource
+from synapse.handlers.receipts import ReceiptEventSource
 from synapse.handlers.room import RoomEventSource
 from synapse.handlers.typing import TypingNotificationEventSource
-from synapse.handlers.receipts import ReceiptEventSource
-from synapse.handlers.account_data import AccountDataEventSource
+from synapse.types import StreamToken
 
 
 class EventSources(object):
diff --git a/synapse/types.py b/synapse/types.py
index cc7c182a78..08f058f714 100644
--- a/synapse/types.py
+++ b/synapse/types.py
@@ -13,11 +13,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import string
+from collections import namedtuple
 
 from synapse.api.errors import SynapseError
 
-from collections import namedtuple
-
 
 class Requester(namedtuple("Requester", [
     "user", "access_token_id", "is_guest", "device_id", "app_service",
diff --git a/synapse/util/__init__.py b/synapse/util/__init__.py
index e9886ef299..680ea928c7 100644
--- a/synapse/util/__init__.py
+++ b/synapse/util/__init__.py
@@ -17,6 +17,7 @@ import logging
 from itertools import islice
 
 import attr
+
 from twisted.internet import defer, task
 
 from synapse.util.logcontext import PreserveLoggingContext
diff --git a/synapse/util/async.py b/synapse/util/async.py
index 1668df4ce6..5d0fb39130 100644
--- a/synapse/util/async.py
+++ b/synapse/util/async.py
@@ -13,20 +13,22 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import logging
+from contextlib import contextmanager
+
+from six.moves import range
+
 from twisted.internet import defer
 from twisted.internet.defer import CancelledError
 from twisted.python import failure
 
+from synapse.util import Clock, logcontext, unwrapFirstError
+
 from .logcontext import (
-    PreserveLoggingContext, make_deferred_yieldable, run_in_background
+    PreserveLoggingContext,
+    make_deferred_yieldable,
+    run_in_background,
 )
-from synapse.util import logcontext, unwrapFirstError, Clock
-
-from contextlib import contextmanager
-
-import logging
-
-from six.moves import range
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/util/caches/__init__.py b/synapse/util/caches/__init__.py
index 900575eb3c..7b065b195e 100644
--- a/synapse/util/caches/__init__.py
+++ b/synapse/util/caches/__init__.py
@@ -13,12 +13,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from prometheus_client.core import Gauge, REGISTRY, GaugeMetricFamily
-
 import os
 
-from six.moves import intern
 import six
+from six.moves import intern
+
+from prometheus_client.core import REGISTRY, Gauge, GaugeMetricFamily
 
 CACHE_SIZE_FACTOR = float(os.environ.get("SYNAPSE_CACHE_FACTOR", 0.5))
 
diff --git a/synapse/util/caches/descriptors.py b/synapse/util/caches/descriptors.py
index 65a1042de1..f8a07df6b8 100644
--- a/synapse/util/caches/descriptors.py
+++ b/synapse/util/caches/descriptors.py
@@ -13,10 +13,19 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+import functools
+import inspect
 import logging
+import threading
+from collections import namedtuple
 
+import six
+from six import itervalues, string_types
+
+from twisted.internet import defer
+
+from synapse.util import logcontext, unwrapFirstError
 from synapse.util.async import ObservableDeferred
-from synapse.util import unwrapFirstError, logcontext
 from synapse.util.caches import get_cache_factor_for
 from synapse.util.caches.lrucache import LruCache
 from synapse.util.caches.treecache import TreeCache, iterate_tree_cache_entry
@@ -24,17 +33,6 @@ from synapse.util.stringutils import to_ascii
 
 from . import register_cache
 
-from twisted.internet import defer
-from collections import namedtuple
-
-import functools
-import inspect
-import threading
-
-from six import string_types, itervalues
-import six
-
-
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/util/caches/dictionary_cache.py b/synapse/util/caches/dictionary_cache.py
index 95793d466d..6c0b5a4094 100644
--- a/synapse/util/caches/dictionary_cache.py
+++ b/synapse/util/caches/dictionary_cache.py
@@ -13,12 +13,13 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.util.caches.lrucache import LruCache
-from collections import namedtuple
-from . import register_cache
-import threading
 import logging
+import threading
+from collections import namedtuple
 
+from synapse.util.caches.lrucache import LruCache
+
+from . import register_cache
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/util/caches/expiringcache.py b/synapse/util/caches/expiringcache.py
index ff04c91955..4abca91f6d 100644
--- a/synapse/util/caches/expiringcache.py
+++ b/synapse/util/caches/expiringcache.py
@@ -13,11 +13,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.util.caches import register_cache
-
-from collections import OrderedDict
 import logging
+from collections import OrderedDict
 
+from synapse.util.caches import register_cache
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/util/caches/lrucache.py b/synapse/util/caches/lrucache.py
index 1c5a982094..b684f24e7b 100644
--- a/synapse/util/caches/lrucache.py
+++ b/synapse/util/caches/lrucache.py
@@ -14,8 +14,8 @@
 # limitations under the License.
 
 
-from functools import wraps
 import threading
+from functools import wraps
 
 from synapse.util.caches.treecache import TreeCache
 
diff --git a/synapse/util/caches/stream_change_cache.py b/synapse/util/caches/stream_change_cache.py
index 0fb8620001..8637867c6d 100644
--- a/synapse/util/caches/stream_change_cache.py
+++ b/synapse/util/caches/stream_change_cache.py
@@ -13,12 +13,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.util import caches
-
-
-from sortedcontainers import SortedDict
 import logging
 
+from sortedcontainers import SortedDict
+
+from synapse.util import caches
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/util/file_consumer.py b/synapse/util/file_consumer.py
index c78801015b..629ed44149 100644
--- a/synapse/util/file_consumer.py
+++ b/synapse/util/file_consumer.py
@@ -13,12 +13,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from six.moves import queue
+
 from twisted.internet import threads
 
 from synapse.util.logcontext import make_deferred_yieldable, run_in_background
 
-from six.moves import queue
-
 
 class BackgroundFileConsumer(object):
     """A consumer that writes to a file like object. Supports both push
diff --git a/synapse/util/frozenutils.py b/synapse/util/frozenutils.py
index 535e7d0e7a..581c6052ac 100644
--- a/synapse/util/frozenutils.py
+++ b/synapse/util/frozenutils.py
@@ -13,11 +13,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from frozendict import frozendict
-from canonicaljson import json
-
 from six import string_types
 
+from canonicaljson import json
+from frozendict import frozendict
+
 
 def freeze(o):
     if isinstance(o, dict):
diff --git a/synapse/util/httpresourcetree.py b/synapse/util/httpresourcetree.py
index e9f0f292ee..2d7ddc1cbe 100644
--- a/synapse/util/httpresourcetree.py
+++ b/synapse/util/httpresourcetree.py
@@ -12,10 +12,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.web.resource import NoResource
-
 import logging
 
+from twisted.web.resource import NoResource
+
 logger = logging.getLogger(__name__)
 
 
diff --git a/synapse/util/logcontext.py b/synapse/util/logcontext.py
index df2b71b791..f6c7175f74 100644
--- a/synapse/util/logcontext.py
+++ b/synapse/util/logcontext.py
@@ -22,10 +22,10 @@ them.
 See doc/log_contexts.rst for details on how this works.
 """
 
-from twisted.internet import defer
-
-import threading
 import logging
+import threading
+
+from twisted.internet import defer
 
 logger = logging.getLogger(__name__)
 
@@ -49,18 +49,107 @@ except Exception:
         return None
 
 
+class ContextResourceUsage(object):
+    """Object for tracking the resources used by a log context
+
+    Attributes:
+        ru_utime (float): user CPU time (in seconds)
+        ru_stime (float): system CPU time (in seconds)
+        db_txn_count (int): number of database transactions done
+        db_sched_duration_sec (float): amount of time spent waiting for a
+            database connection
+        db_txn_duration_sec (float): amount of time spent doing database
+            transactions (excluding scheduling time)
+        evt_db_fetch_count (int): number of events requested from the database
+    """
+
+    __slots__ = [
+        "ru_stime", "ru_utime",
+        "db_txn_count", "db_txn_duration_sec", "db_sched_duration_sec",
+        "evt_db_fetch_count",
+    ]
+
+    def __init__(self, copy_from=None):
+        """Create a new ContextResourceUsage
+
+        Args:
+            copy_from (ContextResourceUsage|None): if not None, an object to
+                copy stats from
+        """
+        if copy_from is None:
+            self.reset()
+        else:
+            self.ru_utime = copy_from.ru_utime
+            self.ru_stime = copy_from.ru_stime
+            self.db_txn_count = copy_from.db_txn_count
+
+            self.db_txn_duration_sec = copy_from.db_txn_duration_sec
+            self.db_sched_duration_sec = copy_from.db_sched_duration_sec
+            self.evt_db_fetch_count = copy_from.evt_db_fetch_count
+
+    def copy(self):
+        return ContextResourceUsage(copy_from=self)
+
+    def reset(self):
+        self.ru_stime = 0.
+        self.ru_utime = 0.
+        self.db_txn_count = 0
+
+        self.db_txn_duration_sec = 0
+        self.db_sched_duration_sec = 0
+        self.evt_db_fetch_count = 0
+
+    def __iadd__(self, other):
+        """Add another ContextResourceUsage's stats to this one's.
+
+        Args:
+            other (ContextResourceUsage): the other resource usage object
+        """
+        self.ru_utime += other.ru_utime
+        self.ru_stime += other.ru_stime
+        self.db_txn_count += other.db_txn_count
+        self.db_txn_duration_sec += other.db_txn_duration_sec
+        self.db_sched_duration_sec += other.db_sched_duration_sec
+        self.evt_db_fetch_count += other.evt_db_fetch_count
+        return self
+
+    def __isub__(self, other):
+        self.ru_utime -= other.ru_utime
+        self.ru_stime -= other.ru_stime
+        self.db_txn_count -= other.db_txn_count
+        self.db_txn_duration_sec -= other.db_txn_duration_sec
+        self.db_sched_duration_sec -= other.db_sched_duration_sec
+        self.evt_db_fetch_count -= other.evt_db_fetch_count
+        return self
+
+    def __add__(self, other):
+        res = ContextResourceUsage(copy_from=self)
+        res += other
+        return res
+
+    def __sub__(self, other):
+        res = ContextResourceUsage(copy_from=self)
+        res -= other
+        return res
+
+
 class LoggingContext(object):
     """Additional context for log formatting. Contexts are scoped within a
     "with" block.
 
+    If a parent is given when creating a new context, then:
+        - logging fields are copied from the parent to the new context on entry
+        - when the new context exits, the cpu usage stats are copied from the
+          child to the parent
+
     Args:
         name (str): Name for the context for debugging.
+        parent_context (LoggingContext|None): The parent of the new context
     """
 
     __slots__ = [
-        "previous_context", "name", "ru_stime", "ru_utime",
-        "db_txn_count", "db_txn_duration_sec", "db_sched_duration_sec",
-        "evt_db_fetch_count",
+        "previous_context", "name", "parent_context",
+        "_resource_usage",
         "usage_start",
         "main_thread", "alive",
         "request", "tag",
@@ -100,21 +189,12 @@ class LoggingContext(object):
 
     sentinel = Sentinel()
 
-    def __init__(self, name=None):
+    def __init__(self, name=None, parent_context=None):
         self.previous_context = LoggingContext.current_context()
         self.name = name
-        self.ru_stime = 0.
-        self.ru_utime = 0.
-        self.db_txn_count = 0
 
-        # sec spent waiting for db txns, excluding scheduling time
-        self.db_txn_duration_sec = 0
-
-        # sec spent waiting for db txns to be scheduled
-        self.db_sched_duration_sec = 0
-
-        # number of events this thread has fetched from the db
-        self.evt_db_fetch_count = 0
+        # track the resources used by this context so far
+        self._resource_usage = ContextResourceUsage()
 
         # If alive has the thread resource usage when the logcontext last
         # became active.
@@ -125,6 +205,8 @@ class LoggingContext(object):
         self.tag = ""
         self.alive = True
 
+        self.parent_context = parent_context
+
     def __str__(self):
         return "%s@%x" % (self.name, id(self))
 
@@ -162,6 +244,10 @@ class LoggingContext(object):
                 self.previous_context, old_context
             )
         self.alive = True
+
+        if self.parent_context is not None:
+            self.parent_context.copy_to(self)
+
         return self
 
     def __exit__(self, type, value, traceback):
@@ -183,6 +269,13 @@ class LoggingContext(object):
         self.previous_context = None
         self.alive = False
 
+        # if we have a parent, pass our CPU usage stats on
+        if self.parent_context is not None:
+            self.parent_context._resource_usage += self._resource_usage
+
+            # reset them in case we get entered again
+            self._resource_usage.reset()
+
     def copy_to(self, record):
         """Copy logging fields from this context to a log record or
         another LoggingContext
@@ -207,39 +300,43 @@ class LoggingContext(object):
             logger.warning("Stopped logcontext %s on different thread", self)
             return
 
-        # When we stop, let's record the resource used since we started
-        if self.usage_start:
-            usage_end = get_thread_resource_usage()
+        # When we stop, let's record the cpu used since we started
+        if not self.usage_start:
+            logger.warning(
+                "Called stop on logcontext %s without calling start", self,
+            )
+            return
 
-            self.ru_utime += usage_end.ru_utime - self.usage_start.ru_utime
-            self.ru_stime += usage_end.ru_stime - self.usage_start.ru_stime
+        usage_end = get_thread_resource_usage()
 
-            self.usage_start = None
-        else:
-            logger.warning("Called stop on logcontext %s without calling start", self)
+        self._resource_usage.ru_utime += usage_end.ru_utime - self.usage_start.ru_utime
+        self._resource_usage.ru_stime += usage_end.ru_stime - self.usage_start.ru_stime
+
+        self.usage_start = None
 
     def get_resource_usage(self):
-        """Get CPU time used by this logcontext so far.
+        """Get resources used by this logcontext so far.
 
         Returns:
-            tuple[float, float]: The user and system CPU usage in seconds
+            ContextResourceUsage: a *copy* of the object tracking resource
+                usage so far
         """
-        ru_utime = self.ru_utime
-        ru_stime = self.ru_stime
+        # we always return a copy, for consistency
+        res = self._resource_usage.copy()
 
         # If we are on the correct thread and we're currently running then we
         # can include resource usage so far.
         is_main_thread = threading.current_thread() is self.main_thread
         if self.alive and self.usage_start and is_main_thread:
             current = get_thread_resource_usage()
-            ru_utime += current.ru_utime - self.usage_start.ru_utime
-            ru_stime += current.ru_stime - self.usage_start.ru_stime
+            res.ru_utime += current.ru_utime - self.usage_start.ru_utime
+            res.ru_stime += current.ru_stime - self.usage_start.ru_stime
 
-        return ru_utime, ru_stime
+        return res
 
     def add_database_transaction(self, duration_sec):
-        self.db_txn_count += 1
-        self.db_txn_duration_sec += duration_sec
+        self._resource_usage.db_txn_count += 1
+        self._resource_usage.db_txn_duration_sec += duration_sec
 
     def add_database_scheduled(self, sched_sec):
         """Record a use of the database pool
@@ -248,7 +345,7 @@ class LoggingContext(object):
             sched_sec (float): number of seconds it took us to get a
                 connection
         """
-        self.db_sched_duration_sec += sched_sec
+        self._resource_usage.db_sched_duration_sec += sched_sec
 
     def record_event_fetch(self, event_count):
         """Record a number of events being fetched from the db
@@ -256,7 +353,7 @@ class LoggingContext(object):
         Args:
             event_count (int): number of events being fetched
         """
-        self.evt_db_fetch_count += event_count
+        self._resource_usage.evt_db_fetch_count += event_count
 
 
 class LoggingContextFilter(logging.Filter):
diff --git a/synapse/util/logformatter.py b/synapse/util/logformatter.py
index 3e42868ea9..a46bc47ce3 100644
--- a/synapse/util/logformatter.py
+++ b/synapse/util/logformatter.py
@@ -14,10 +14,11 @@
 # limitations under the License.
 
 
-from six import StringIO
 import logging
 import traceback
 
+from six import StringIO
+
 
 class LogFormatter(logging.Formatter):
     """Log formatter which gives more detail for exceptions
diff --git a/synapse/util/logutils.py b/synapse/util/logutils.py
index 03249c5dc8..62a00189cc 100644
--- a/synapse/util/logutils.py
+++ b/synapse/util/logutils.py
@@ -14,13 +14,11 @@
 # limitations under the License.
 
 
-from inspect import getcallargs
-from functools import wraps
-
-import logging
 import inspect
+import logging
 import time
-
+from functools import wraps
+from inspect import getcallargs
 
 _TIME_FUNC_ID = 0
 
diff --git a/synapse/util/manhole.py b/synapse/util/manhole.py
index 97e0f00b67..14be3c7396 100644
--- a/synapse/util/manhole.py
+++ b/synapse/util/manhole.py
@@ -12,11 +12,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.conch.manhole import ColoredManhole
-from twisted.conch.insults import insults
 from twisted.conch import manhole_ssh
-from twisted.cred import checkers, portal
+from twisted.conch.insults import insults
+from twisted.conch.manhole import ColoredManhole
 from twisted.conch.ssh.keys import Key
+from twisted.cred import checkers, portal
 
 PUBLIC_KEY = (
     "ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAGEArzJx8OYOnJmzf4tfBEvLi8DVPrJ3/c9k2I/Az"
diff --git a/synapse/util/metrics.py b/synapse/util/metrics.py
index 1ba7d65c7c..6ba7107896 100644
--- a/synapse/util/metrics.py
+++ b/synapse/util/metrics.py
@@ -13,15 +13,15 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer
+import logging
+from functools import wraps
 
 from prometheus_client import Counter
+
+from twisted.internet import defer
+
 from synapse.util.logcontext import LoggingContext
 
-from functools import wraps
-import logging
-
-
 logger = logging.getLogger(__name__)
 
 block_counter = Counter("synapse_util_metrics_block_count", "", ["block_name"])
@@ -60,10 +60,9 @@ def measure_func(name):
 
 class Measure(object):
     __slots__ = [
-        "clock", "name", "start_context", "start", "new_context", "ru_utime",
-        "ru_stime",
-        "db_txn_count", "db_txn_duration_sec", "db_sched_duration_sec",
+        "clock", "name", "start_context", "start",
         "created_context",
+        "start_usage",
     ]
 
     def __init__(self, clock, name):
@@ -81,10 +80,7 @@ class Measure(object):
             self.start_context.__enter__()
             self.created_context = True
 
-        self.ru_utime, self.ru_stime = self.start_context.get_resource_usage()
-        self.db_txn_count = self.start_context.db_txn_count
-        self.db_txn_duration_sec = self.start_context.db_txn_duration_sec
-        self.db_sched_duration_sec = self.start_context.db_sched_duration_sec
+        self.start_usage = self.start_context.get_resource_usage()
 
     def __exit__(self, exc_type, exc_val, exc_tb):
         if isinstance(exc_type, Exception) or not self.start_context:
@@ -108,15 +104,12 @@ class Measure(object):
             logger.warn("Expected context. (%r)", self.name)
             return
 
-        ru_utime, ru_stime = context.get_resource_usage()
-
-        block_ru_utime.labels(self.name).inc(ru_utime - self.ru_utime)
-        block_ru_stime.labels(self.name).inc(ru_stime - self.ru_stime)
-        block_db_txn_count.labels(self.name).inc(context.db_txn_count - self.db_txn_count)
-        block_db_txn_duration.labels(self.name).inc(
-            context.db_txn_duration_sec - self.db_txn_duration_sec)
-        block_db_sched_duration.labels(self.name).inc(
-            context.db_sched_duration_sec - self.db_sched_duration_sec)
+        usage = context.get_resource_usage() - self.start_usage
+        block_ru_utime.labels(self.name).inc(usage.ru_utime)
+        block_ru_stime.labels(self.name).inc(usage.ru_stime)
+        block_db_txn_count.labels(self.name).inc(usage.db_txn_count)
+        block_db_txn_duration.labels(self.name).inc(usage.db_txn_duration_sec)
+        block_db_sched_duration.labels(self.name).inc(usage.db_sched_duration_sec)
 
         if self.created_context:
             self.start_context.__exit__(exc_type, exc_val, exc_tb)
diff --git a/synapse/util/msisdn.py b/synapse/util/msisdn.py
index 607161e7f0..a6c30e5265 100644
--- a/synapse/util/msisdn.py
+++ b/synapse/util/msisdn.py
@@ -14,6 +14,7 @@
 # limitations under the License.
 
 import phonenumbers
+
 from synapse.api.errors import SynapseError
 
 
diff --git a/synapse/util/ratelimitutils.py b/synapse/util/ratelimitutils.py
index c5a45cef7c..5ac33b2132 100644
--- a/synapse/util/ratelimitutils.py
+++ b/synapse/util/ratelimitutils.py
@@ -13,19 +13,18 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer
-
-from synapse.api.errors import LimitExceededError
-
-from synapse.util.logcontext import (
-    run_in_background, make_deferred_yieldable,
-    PreserveLoggingContext,
-)
-
 import collections
 import contextlib
 import logging
 
+from twisted.internet import defer
+
+from synapse.api.errors import LimitExceededError
+from synapse.util.logcontext import (
+    PreserveLoggingContext,
+    make_deferred_yieldable,
+    run_in_background,
+)
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/util/retryutils.py b/synapse/util/retryutils.py
index 4e93f69d3a..8a3a06fd74 100644
--- a/synapse/util/retryutils.py
+++ b/synapse/util/retryutils.py
@@ -12,14 +12,13 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-import synapse.util.logcontext
-from twisted.internet import defer
-
-from synapse.api.errors import CodeMessageException
-
 import logging
 import random
 
+from twisted.internet import defer
+
+import synapse.util.logcontext
+from synapse.api.errors import CodeMessageException
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/util/rlimit.py b/synapse/util/rlimit.py
index f4a9abf83f..6c0f2bb0cf 100644
--- a/synapse/util/rlimit.py
+++ b/synapse/util/rlimit.py
@@ -13,9 +13,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import resource
 import logging
-
+import resource
 
 logger = logging.getLogger("synapse.app.homeserver")
 
diff --git a/synapse/util/stringutils.py b/synapse/util/stringutils.py
index b98b9dc6e4..43d9db67ec 100644
--- a/synapse/util/stringutils.py
+++ b/synapse/util/stringutils.py
@@ -15,6 +15,7 @@
 
 import random
 import string
+
 from six.moves import range
 
 _string_with_symbols = (
diff --git a/synapse/util/versionstring.py b/synapse/util/versionstring.py
index 52086df465..1fbcd41115 100644
--- a/synapse/util/versionstring.py
+++ b/synapse/util/versionstring.py
@@ -14,9 +14,9 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import subprocess
-import os
 import logging
+import os
+import subprocess
 
 logger = logging.getLogger(__name__)
 
diff --git a/synapse/visibility.py b/synapse/visibility.py
index 65d79cf0d0..015c2bab37 100644
--- a/synapse/visibility.py
+++ b/synapse/visibility.py
@@ -20,9 +20,7 @@ from twisted.internet import defer
 
 from synapse.api.constants import EventTypes, Membership
 from synapse.events.utils import prune_event
-from synapse.util.logcontext import (
-    make_deferred_yieldable, preserve_fn,
-)
+from synapse.util.logcontext import make_deferred_yieldable, preserve_fn
 
 logger = logging.getLogger(__name__)
 
diff --git a/tests/__init__.py b/tests/__init__.py
index aab20e8e02..24006c949e 100644
--- a/tests/__init__.py
+++ b/tests/__init__.py
@@ -14,4 +14,5 @@
 # limitations under the License.
 
 from twisted.trial import util
+
 util.DEFAULT_TIMEOUT_DURATION = 10
diff --git a/tests/api/test_auth.py b/tests/api/test_auth.py
index aec3b62897..5f158ec4b9 100644
--- a/tests/api/test_auth.py
+++ b/tests/api/test_auth.py
@@ -13,16 +13,19 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import pymacaroons
 from mock import Mock
+
+import pymacaroons
+
 from twisted.internet import defer
 
 import synapse.handlers.auth
 from synapse.api.auth import Auth
 from synapse.api.errors import AuthError
 from synapse.types import UserID
+
 from tests import unittest
-from tests.utils import setup_test_homeserver, mock_getRawHeaders
+from tests.utils import mock_getRawHeaders, setup_test_homeserver
 
 
 class TestHandlers(object):
diff --git a/tests/api/test_filtering.py b/tests/api/test_filtering.py
index dcceca7f3e..836a23fb54 100644
--- a/tests/api/test_filtering.py
+++ b/tests/api/test_filtering.py
@@ -13,20 +13,19 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from tests import unittest
-from twisted.internet import defer
-
 from mock import Mock
-from tests.utils import (
-    MockHttpResource, DeferredMockCallable, setup_test_homeserver
-)
-
-from synapse.api.filtering import Filter
-from synapse.events import FrozenEvent
-from synapse.api.errors import SynapseError
 
 import jsonschema
 
+from twisted.internet import defer
+
+from synapse.api.errors import SynapseError
+from synapse.api.filtering import Filter
+from synapse.events import FrozenEvent
+
+from tests import unittest
+from tests.utils import DeferredMockCallable, MockHttpResource, setup_test_homeserver
+
 user_localpart = "test_user"
 
 
diff --git a/tests/appservice/test_appservice.py b/tests/appservice/test_appservice.py
index 5b2b95860a..891e0cc973 100644
--- a/tests/appservice/test_appservice.py
+++ b/tests/appservice/test_appservice.py
@@ -12,14 +12,15 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-from synapse.appservice import ApplicationService
+import re
+
+from mock import Mock
 
 from twisted.internet import defer
 
-from mock import Mock
-from tests import unittest
+from synapse.appservice import ApplicationService
 
-import re
+from tests import unittest
 
 
 def _regex(regex, exclusive=True):
diff --git a/tests/appservice/test_scheduler.py b/tests/appservice/test_scheduler.py
index 9181692771..b9f4863e9a 100644
--- a/tests/appservice/test_scheduler.py
+++ b/tests/appservice/test_scheduler.py
@@ -12,17 +12,22 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-from synapse.appservice import ApplicationServiceState
-from synapse.appservice.scheduler import (
-    _ServiceQueuer, _TransactionController, _Recoverer
-)
+from mock import Mock
+
 from twisted.internet import defer
 
+from synapse.appservice import ApplicationServiceState
+from synapse.appservice.scheduler import (
+    _Recoverer,
+    _ServiceQueuer,
+    _TransactionController,
+)
 from synapse.util.logcontext import make_deferred_yieldable
-from ..utils import MockClock
-from mock import Mock
+
 from tests import unittest
 
+from ..utils import MockClock
+
 
 class ApplicationServiceSchedulerTransactionCtrlTestCase(unittest.TestCase):
 
diff --git a/tests/config/test_generate.py b/tests/config/test_generate.py
index 879159ccea..eb7f0ab12a 100644
--- a/tests/config/test_generate.py
+++ b/tests/config/test_generate.py
@@ -19,6 +19,7 @@ import shutil
 import tempfile
 
 from synapse.config.homeserver import HomeServerConfig
+
 from tests import unittest
 
 
diff --git a/tests/config/test_load.py b/tests/config/test_load.py
index 772afd2cf9..5c422eff38 100644
--- a/tests/config/test_load.py
+++ b/tests/config/test_load.py
@@ -15,8 +15,11 @@
 import os.path
 import shutil
 import tempfile
+
 import yaml
+
 from synapse.config.homeserver import HomeServerConfig
+
 from tests import unittest
 
 
diff --git a/tests/crypto/test_event_signing.py b/tests/crypto/test_event_signing.py
index 47cb328a01..cd11871b80 100644
--- a/tests/crypto/test_event_signing.py
+++ b/tests/crypto/test_event_signing.py
@@ -14,15 +14,13 @@
 # limitations under the License.
 
 
-from tests import unittest
-
-from synapse.events.builder import EventBuilder
-from synapse.crypto.event_signing import add_hashes_and_signatures
-
+import nacl.signing
 from unpaddedbase64 import decode_base64
 
-import nacl.signing
+from synapse.crypto.event_signing import add_hashes_and_signatures
+from synapse.events.builder import EventBuilder
 
+from tests import unittest
 
 # Perform these tests using given secret key so we get entirely deterministic
 # signatures output that we can test against.
diff --git a/tests/crypto/test_keyring.py b/tests/crypto/test_keyring.py
index cc1c862ba4..a9d37fe084 100644
--- a/tests/crypto/test_keyring.py
+++ b/tests/crypto/test_keyring.py
@@ -14,15 +14,19 @@
 # limitations under the License.
 import time
 
+from mock import Mock
+
 import signedjson.key
 import signedjson.sign
-from mock import Mock
+
+from twisted.internet import defer, reactor
+
 from synapse.api.errors import SynapseError
 from synapse.crypto import keyring
-from synapse.util import logcontext, Clock
+from synapse.util import Clock, logcontext
 from synapse.util.logcontext import LoggingContext
+
 from tests import unittest, utils
-from twisted.internet import defer, reactor
 
 
 class MockPerspectiveServer(object):
diff --git a/tests/events/test_utils.py b/tests/events/test_utils.py
index dfc870066e..f51d99419e 100644
--- a/tests/events/test_utils.py
+++ b/tests/events/test_utils.py
@@ -14,11 +14,11 @@
 # limitations under the License.
 
 
-from .. import unittest
-
 from synapse.events import FrozenEvent
 from synapse.events.utils import prune_event, serialize_event
 
+from .. import unittest
+
 
 def MockEvent(**kwargs):
     if "event_id" not in kwargs:
diff --git a/tests/federation/test_federation_server.py b/tests/federation/test_federation_server.py
index 4e8dc8fea0..c91e25f54f 100644
--- a/tests/federation/test_federation_server.py
+++ b/tests/federation/test_federation_server.py
@@ -16,6 +16,7 @@ import logging
 
 from synapse.events import FrozenEvent
 from synapse.federation.federation_server import server_matches_acl_event
+
 from tests import unittest
 
 
diff --git a/tests/handlers/test_appservice.py b/tests/handlers/test_appservice.py
index b753455943..57c0771cf3 100644
--- a/tests/handlers/test_appservice.py
+++ b/tests/handlers/test_appservice.py
@@ -13,13 +13,15 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from mock import Mock
+
 from twisted.internet import defer
-from .. import unittest
-from tests.utils import MockClock
 
 from synapse.handlers.appservice import ApplicationServicesHandler
 
-from mock import Mock
+from tests.utils import MockClock
+
+from .. import unittest
 
 
 class AppServiceHandlerTestCase(unittest.TestCase):
diff --git a/tests/handlers/test_auth.py b/tests/handlers/test_auth.py
index 1822dcf1e0..2e5e8e4dec 100644
--- a/tests/handlers/test_auth.py
+++ b/tests/handlers/test_auth.py
@@ -14,11 +14,13 @@
 # limitations under the License.
 
 import pymacaroons
+
 from twisted.internet import defer
 
 import synapse
 import synapse.api.errors
 from synapse.handlers.auth import AuthHandler
+
 from tests import unittest
 from tests.utils import setup_test_homeserver
 
diff --git a/tests/handlers/test_device.py b/tests/handlers/test_device.py
index 778ff2f6e9..633a0b7f36 100644
--- a/tests/handlers/test_device.py
+++ b/tests/handlers/test_device.py
@@ -17,8 +17,8 @@ from twisted.internet import defer
 
 import synapse.api.errors
 import synapse.handlers.device
-
 import synapse.storage
+
 from tests import unittest, utils
 
 user1 = "@boris:aaa"
diff --git a/tests/handlers/test_directory.py b/tests/handlers/test_directory.py
index 7e5332e272..a353070316 100644
--- a/tests/handlers/test_directory.py
+++ b/tests/handlers/test_directory.py
@@ -14,14 +14,14 @@
 # limitations under the License.
 
 
-from tests import unittest
-from twisted.internet import defer
-
 from mock import Mock
 
+from twisted.internet import defer
+
 from synapse.handlers.directory import DirectoryHandler
 from synapse.types import RoomAlias
 
+from tests import unittest
 from tests.utils import setup_test_homeserver
 
 
diff --git a/tests/handlers/test_e2e_keys.py b/tests/handlers/test_e2e_keys.py
index d1bd87b898..ca1542236d 100644
--- a/tests/handlers/test_e2e_keys.py
+++ b/tests/handlers/test_e2e_keys.py
@@ -14,13 +14,14 @@
 # limitations under the License.
 
 import mock
-from synapse.api import errors
+
 from twisted.internet import defer
 
 import synapse.api.errors
 import synapse.handlers.e2e_keys
-
 import synapse.storage
+from synapse.api import errors
+
 from tests import unittest, utils
 
 
diff --git a/tests/handlers/test_presence.py b/tests/handlers/test_presence.py
index de06a6ad30..121ce78634 100644
--- a/tests/handlers/test_presence.py
+++ b/tests/handlers/test_presence.py
@@ -14,18 +14,22 @@
 # limitations under the License.
 
 
-from tests import unittest
-
 from mock import Mock, call
 
 from synapse.api.constants import PresenceState
 from synapse.handlers.presence import (
-    handle_update, handle_timeout,
-    IDLE_TIMER, SYNC_ONLINE_TIMEOUT, LAST_ACTIVE_GRANULARITY, FEDERATION_TIMEOUT,
     FEDERATION_PING_INTERVAL,
+    FEDERATION_TIMEOUT,
+    IDLE_TIMER,
+    LAST_ACTIVE_GRANULARITY,
+    SYNC_ONLINE_TIMEOUT,
+    handle_timeout,
+    handle_update,
 )
 from synapse.storage.presence import UserPresenceState
 
+from tests import unittest
+
 
 class PresenceUpdateTestCase(unittest.TestCase):
     def test_offline_to_online(self):
diff --git a/tests/handlers/test_profile.py b/tests/handlers/test_profile.py
index 458296ee4c..dc17918a3d 100644
--- a/tests/handlers/test_profile.py
+++ b/tests/handlers/test_profile.py
@@ -14,16 +14,16 @@
 # limitations under the License.
 
 
-from tests import unittest
-from twisted.internet import defer
-
 from mock import Mock, NonCallableMock
 
+from twisted.internet import defer
+
 import synapse.types
 from synapse.api.errors import AuthError
 from synapse.handlers.profile import ProfileHandler
 from synapse.types import UserID
 
+from tests import unittest
 from tests.utils import setup_test_homeserver
 
 
diff --git a/tests/handlers/test_register.py b/tests/handlers/test_register.py
index e990e45220..025fa1be81 100644
--- a/tests/handlers/test_register.py
+++ b/tests/handlers/test_register.py
@@ -13,15 +13,16 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from mock import Mock
+
 from twisted.internet import defer
-from .. import unittest
 
 from synapse.handlers.register import RegistrationHandler
 from synapse.types import UserID, create_requester
 
 from tests.utils import setup_test_homeserver
 
-from mock import Mock
+from .. import unittest
 
 
 class RegistrationHandlers(object):
diff --git a/tests/handlers/test_typing.py b/tests/handlers/test_typing.py
index a433bbfa8a..b08856f763 100644
--- a/tests/handlers/test_typing.py
+++ b/tests/handlers/test_typing.py
@@ -14,19 +14,24 @@
 # limitations under the License.
 
 
-from tests import unittest
-from twisted.internet import defer
-
-from mock import Mock, call, ANY
 import json
 
-from ..utils import (
-    MockHttpResource, MockClock, DeferredMockCallable, setup_test_homeserver
-)
+from mock import ANY, Mock, call
+
+from twisted.internet import defer
 
 from synapse.api.errors import AuthError
 from synapse.types import UserID
 
+from tests import unittest
+
+from ..utils import (
+    DeferredMockCallable,
+    MockClock,
+    MockHttpResource,
+    setup_test_homeserver,
+)
+
 
 def _expect_edu(destination, edu_type, content, origin="test"):
     return {
diff --git a/tests/http/test_endpoint.py b/tests/http/test_endpoint.py
index b8a48d20a4..60e6a75953 100644
--- a/tests/http/test_endpoint.py
+++ b/tests/http/test_endpoint.py
@@ -12,10 +12,8 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-from synapse.http.endpoint import (
-    parse_server_name,
-    parse_and_validate_server_name,
-)
+from synapse.http.endpoint import parse_and_validate_server_name, parse_server_name
+
 from tests import unittest
 
 
diff --git a/tests/replication/slave/storage/_base.py b/tests/replication/slave/storage/_base.py
index 64e07a8c93..8708c8a196 100644
--- a/tests/replication/slave/storage/_base.py
+++ b/tests/replication/slave/storage/_base.py
@@ -12,17 +12,20 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from twisted.internet import defer, reactor
-from tests import unittest
-
 import tempfile
 
 from mock import Mock, NonCallableMock
-from tests.utils import setup_test_homeserver
-from synapse.replication.tcp.resource import ReplicationStreamProtocolFactory
+
+from twisted.internet import defer, reactor
+
 from synapse.replication.tcp.client import (
-    ReplicationClientHandler, ReplicationClientFactory,
+    ReplicationClientFactory,
+    ReplicationClientHandler,
 )
+from synapse.replication.tcp.resource import ReplicationStreamProtocolFactory
+
+from tests import unittest
+from tests.utils import setup_test_homeserver
 
 
 class BaseSlavedStoreTestCase(unittest.TestCase):
diff --git a/tests/replication/slave/storage/test_account_data.py b/tests/replication/slave/storage/test_account_data.py
index f47a42e45d..adf226404e 100644
--- a/tests/replication/slave/storage/test_account_data.py
+++ b/tests/replication/slave/storage/test_account_data.py
@@ -13,11 +13,11 @@
 # limitations under the License.
 
 
-from ._base import BaseSlavedStoreTestCase
+from twisted.internet import defer
 
 from synapse.replication.slave.storage.account_data import SlavedAccountDataStore
 
-from twisted.internet import defer
+from ._base import BaseSlavedStoreTestCase
 
 USER_ID = "@feeling:blue"
 TYPE = "my.type"
diff --git a/tests/replication/slave/storage/test_events.py b/tests/replication/slave/storage/test_events.py
index cb058d3142..cea01d93eb 100644
--- a/tests/replication/slave/storage/test_events.py
+++ b/tests/replication/slave/storage/test_events.py
@@ -12,15 +12,14 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import BaseSlavedStoreTestCase
+from twisted.internet import defer
 
 from synapse.events import FrozenEvent, _EventInternalMetadata
 from synapse.events.snapshot import EventContext
 from synapse.replication.slave.storage.events import SlavedEventStore
 from synapse.storage.roommember import RoomsForUser
 
-from twisted.internet import defer
-
+from ._base import BaseSlavedStoreTestCase
 
 USER_ID = "@feeling:blue"
 USER_ID_2 = "@bright:blue"
diff --git a/tests/replication/slave/storage/test_receipts.py b/tests/replication/slave/storage/test_receipts.py
index 6624fe4eea..e6d670cc1f 100644
--- a/tests/replication/slave/storage/test_receipts.py
+++ b/tests/replication/slave/storage/test_receipts.py
@@ -12,11 +12,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from ._base import BaseSlavedStoreTestCase
+from twisted.internet import defer
 
 from synapse.replication.slave.storage.receipts import SlavedReceiptsStore
 
-from twisted.internet import defer
+from ._base import BaseSlavedStoreTestCase
 
 USER_ID = "@feeling:blue"
 ROOM_ID = "!room:blue"
diff --git a/tests/rest/client/test_transactions.py b/tests/rest/client/test_transactions.py
index 6a757289db..eee99ca2e0 100644
--- a/tests/rest/client/test_transactions.py
+++ b/tests/rest/client/test_transactions.py
@@ -1,10 +1,11 @@
-from synapse.rest.client.transactions import HttpTransactionCache
-from synapse.rest.client.transactions import CLEANUP_PERIOD_MS
-from twisted.internet import defer, reactor
 from mock import Mock, call
 
+from twisted.internet import defer, reactor
+
+from synapse.rest.client.transactions import CLEANUP_PERIOD_MS, HttpTransactionCache
 from synapse.util import Clock
 from synapse.util.logcontext import LoggingContext
+
 from tests import unittest
 from tests.utils import MockClock
 
diff --git a/tests/rest/client/v1/test_events.py b/tests/rest/client/v1/test_events.py
index f5a7258e68..a5af36a99c 100644
--- a/tests/rest/client/v1/test_events.py
+++ b/tests/rest/client/v1/test_events.py
@@ -14,7 +14,7 @@
 # limitations under the License.
 
 """ Tests REST events for /events paths."""
-from tests import unittest
+from mock import Mock, NonCallableMock
 
 # twisted imports
 from twisted.internet import defer
@@ -23,13 +23,11 @@ import synapse.rest.client.v1.events
 import synapse.rest.client.v1.register
 import synapse.rest.client.v1.room
 
+from tests import unittest
 
 from ....utils import MockHttpResource, setup_test_homeserver
 from .utils import RestTestCase
 
-from mock import Mock, NonCallableMock
-
-
 PATH_PREFIX = "/_matrix/client/api/v1"
 
 
diff --git a/tests/rest/client/v1/test_profile.py b/tests/rest/client/v1/test_profile.py
index dc94b8bd19..d71cc8e0db 100644
--- a/tests/rest/client/v1/test_profile.py
+++ b/tests/rest/client/v1/test_profile.py
@@ -15,12 +15,15 @@
 
 """Tests REST events for /profile paths."""
 from mock import Mock
+
 from twisted.internet import defer
 
 import synapse.types
-from synapse.api.errors import SynapseError, AuthError
+from synapse.api.errors import AuthError, SynapseError
 from synapse.rest.client.v1 import profile
+
 from tests import unittest
+
 from ....utils import MockHttpResource, setup_test_homeserver
 
 myid = "@1234ABCD:test"
diff --git a/tests/rest/client/v1/test_register.py b/tests/rest/client/v1/test_register.py
index a6a4e2ffe0..f596acb85f 100644
--- a/tests/rest/client/v1/test_register.py
+++ b/tests/rest/client/v1/test_register.py
@@ -13,12 +13,16 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.rest.client.v1.register import CreateUserRestServlet
-from twisted.internet import defer
+import json
+
 from mock import Mock
+
+from twisted.internet import defer
+
+from synapse.rest.client.v1.register import CreateUserRestServlet
+
 from tests import unittest
 from tests.utils import mock_getRawHeaders
-import json
 
 
 class CreateUserServletTestCase(unittest.TestCase):
diff --git a/tests/rest/client/v1/test_rooms.py b/tests/rest/client/v1/test_rooms.py
index 5bc0ba1934..4e8e49fbe2 100644
--- a/tests/rest/client/v1/test_rooms.py
+++ b/tests/rest/client/v1/test_rooms.py
@@ -15,22 +15,21 @@
 
 """Tests REST events for /rooms paths."""
 
+import json
+
+from mock import Mock, NonCallableMock
+from six.moves.urllib import parse as urlparse
+
 # twisted imports
 from twisted.internet import defer
 
 import synapse.rest.client.v1.room
 from synapse.api.constants import Membership
-
 from synapse.types import UserID
 
-import json
-from six.moves.urllib import parse as urlparse
-
 from ....utils import MockHttpResource, setup_test_homeserver
 from .utils import RestTestCase
 
-from mock import Mock, NonCallableMock
-
 PATH_PREFIX = "/_matrix/client/api/v1"
 
 
diff --git a/tests/rest/client/v1/test_typing.py b/tests/rest/client/v1/test_typing.py
index fe161ee5cb..bddb3302e4 100644
--- a/tests/rest/client/v1/test_typing.py
+++ b/tests/rest/client/v1/test_typing.py
@@ -15,18 +15,17 @@
 
 """Tests REST events for /rooms paths."""
 
+from mock import Mock, NonCallableMock
+
 # twisted imports
 from twisted.internet import defer
 
 import synapse.rest.client.v1.room
 from synapse.types import UserID
 
-from ....utils import MockHttpResource, MockClock, setup_test_homeserver
+from ....utils import MockClock, MockHttpResource, setup_test_homeserver
 from .utils import RestTestCase
 
-from mock import Mock, NonCallableMock
-
-
 PATH_PREFIX = "/_matrix/client/api/v1"
 
 
diff --git a/tests/rest/client/v1/utils.py b/tests/rest/client/v1/utils.py
index 3bb1dd003a..54d7ba380d 100644
--- a/tests/rest/client/v1/utils.py
+++ b/tests/rest/client/v1/utils.py
@@ -13,16 +13,16 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import json
+import time
+
 # twisted imports
 from twisted.internet import defer
 
-# trial imports
-from tests import unittest
-
 from synapse.api.constants import Membership
 
-import json
-import time
+# trial imports
+from tests import unittest
 
 
 class RestTestCase(unittest.TestCase):
diff --git a/tests/rest/client/v2_alpha/__init__.py b/tests/rest/client/v2_alpha/__init__.py
index 5170217d9e..f18a8a6027 100644
--- a/tests/rest/client/v2_alpha/__init__.py
+++ b/tests/rest/client/v2_alpha/__init__.py
@@ -13,16 +13,15 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from tests import unittest
-
 from mock import Mock
 
-from ....utils import MockHttpResource, setup_test_homeserver
-
-from synapse.types import UserID
-
 from twisted.internet import defer
 
+from synapse.types import UserID
+
+from tests import unittest
+
+from ....utils import MockHttpResource, setup_test_homeserver
 
 PATH_PREFIX = "/_matrix/client/v2_alpha"
 
diff --git a/tests/rest/client/v2_alpha/test_filter.py b/tests/rest/client/v2_alpha/test_filter.py
index 76b833e119..bb0b2f94ea 100644
--- a/tests/rest/client/v2_alpha/test_filter.py
+++ b/tests/rest/client/v2_alpha/test_filter.py
@@ -15,16 +15,13 @@
 
 from twisted.internet import defer
 
-from tests import unittest
-
-from synapse.rest.client.v2_alpha import filter
-
-from synapse.api.errors import Codes
-
 import synapse.types
-
+from synapse.api.errors import Codes
+from synapse.rest.client.v2_alpha import filter
 from synapse.types import UserID
 
+from tests import unittest
+
 from ....utils import MockHttpResource, setup_test_homeserver
 
 PATH_PREFIX = "/_matrix/client/v2_alpha"
diff --git a/tests/rest/client/v2_alpha/test_register.py b/tests/rest/client/v2_alpha/test_register.py
index 8aba456510..9b57a56070 100644
--- a/tests/rest/client/v2_alpha/test_register.py
+++ b/tests/rest/client/v2_alpha/test_register.py
@@ -1,12 +1,15 @@
+import json
+
+from mock import Mock
+
+from twisted.internet import defer
 from twisted.python import failure
 
+from synapse.api.errors import InteractiveAuthIncompleteError, SynapseError
 from synapse.rest.client.v2_alpha.register import RegisterRestServlet
-from synapse.api.errors import SynapseError, InteractiveAuthIncompleteError
-from twisted.internet import defer
-from mock import Mock
+
 from tests import unittest
 from tests.utils import mock_getRawHeaders
-import json
 
 
 class RegisterRestServletTestCase(unittest.TestCase):
diff --git a/tests/rest/media/v1/test_media_storage.py b/tests/rest/media/v1/test_media_storage.py
index c5e2f5549a..bf254a260d 100644
--- a/tests/rest/media/v1/test_media_storage.py
+++ b/tests/rest/media/v1/test_media_storage.py
@@ -14,21 +14,21 @@
 # limitations under the License.
 
 
-from twisted.internet import defer, reactor
-
-from synapse.rest.media.v1._base import FileInfo
-from synapse.rest.media.v1.media_storage import MediaStorage
-from synapse.rest.media.v1.filepath import MediaFilePaths
-from synapse.rest.media.v1.storage_provider import FileStorageProviderBackend
-
-from mock import Mock
-
-from tests import unittest
-
 import os
 import shutil
 import tempfile
 
+from mock import Mock
+
+from twisted.internet import defer, reactor
+
+from synapse.rest.media.v1._base import FileInfo
+from synapse.rest.media.v1.filepath import MediaFilePaths
+from synapse.rest.media.v1.media_storage import MediaStorage
+from synapse.rest.media.v1.storage_provider import FileStorageProviderBackend
+
+from tests import unittest
+
 
 class MediaStorageTests(unittest.TestCase):
     def setUp(self):
diff --git a/tests/server.py b/tests/server.py
index 73069dff52..46223ccf05 100644
--- a/tests/server.py
+++ b/tests/server.py
@@ -1,15 +1,17 @@
+import json
 from io import BytesIO
 
-import attr
-import json
 from six import text_type
 
-from twisted.python.failure import Failure
+import attr
+
+from twisted.internet import threads
 from twisted.internet.defer import Deferred
+from twisted.python.failure import Failure
 from twisted.test.proto_helpers import MemoryReactorClock
 
 from synapse.http.site import SynapseRequest
-from twisted.internet import threads
+
 from tests.utils import setup_test_homeserver as _sth
 
 
diff --git a/tests/storage/test__base.py b/tests/storage/test__base.py
index 3cfa21c9f8..6d6f00c5c5 100644
--- a/tests/storage/test__base.py
+++ b/tests/storage/test__base.py
@@ -14,15 +14,15 @@
 # limitations under the License.
 
 
-from tests import unittest
-from twisted.internet import defer
-
 from mock import Mock
 
-from synapse.util.async import ObservableDeferred
+from twisted.internet import defer
 
+from synapse.util.async import ObservableDeferred
 from synapse.util.caches.descriptors import Cache, cached
 
+from tests import unittest
+
 
 class CacheTestCase(unittest.TestCase):
 
diff --git a/tests/storage/test_appservice.py b/tests/storage/test_appservice.py
index 00825498b1..099861b27c 100644
--- a/tests/storage/test_appservice.py
+++ b/tests/storage/test_appservice.py
@@ -12,22 +12,26 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-import tempfile
-from synapse.config._base import ConfigError
-from tests import unittest
-from twisted.internet import defer
-
-from tests.utils import setup_test_homeserver
-from synapse.appservice import ApplicationService, ApplicationServiceState
-from synapse.storage.appservice import (
-    ApplicationServiceStore, ApplicationServiceTransactionStore
-)
-
 import json
 import os
-import yaml
+import tempfile
+
 from mock import Mock
 
+import yaml
+
+from twisted.internet import defer
+
+from synapse.appservice import ApplicationService, ApplicationServiceState
+from synapse.config._base import ConfigError
+from synapse.storage.appservice import (
+    ApplicationServiceStore,
+    ApplicationServiceTransactionStore,
+)
+
+from tests import unittest
+from tests.utils import setup_test_homeserver
+
 
 class ApplicationServiceStoreTestCase(unittest.TestCase):
 
diff --git a/tests/storage/test_background_update.py b/tests/storage/test_background_update.py
index 1286b4ce2d..ab1f310572 100644
--- a/tests/storage/test_background_update.py
+++ b/tests/storage/test_background_update.py
@@ -1,10 +1,10 @@
-from tests import unittest
+from mock import Mock
+
 from twisted.internet import defer
 
+from tests import unittest
 from tests.utils import setup_test_homeserver
 
-from mock import Mock
-
 
 class BackgroundUpdateTestCase(unittest.TestCase):
 
diff --git a/tests/storage/test_base.py b/tests/storage/test_base.py
index 0ac910e76f..1d1234ee39 100644
--- a/tests/storage/test_base.py
+++ b/tests/storage/test_base.py
@@ -14,18 +14,18 @@
 # limitations under the License.
 
 
-from tests import unittest
-from twisted.internet import defer
+from collections import OrderedDict
 
 from mock import Mock
 
-from collections import OrderedDict
+from twisted.internet import defer
 
 from synapse.server import HomeServer
-
 from synapse.storage._base import SQLBaseStore
 from synapse.storage.engines import create_engine
 
+from tests import unittest
+
 
 class SQLBaseStoreTestCase(unittest.TestCase):
     """ Test the "simple" SQL generating methods in SQLBaseStore. """
diff --git a/tests/storage/test_devices.py b/tests/storage/test_devices.py
index f8725acea0..a54cc6bc32 100644
--- a/tests/storage/test_devices.py
+++ b/tests/storage/test_devices.py
@@ -16,6 +16,7 @@
 from twisted.internet import defer
 
 import synapse.api.errors
+
 import tests.unittest
 import tests.utils
 
diff --git a/tests/storage/test_directory.py b/tests/storage/test_directory.py
index 95709cd50a..129ebaf343 100644
--- a/tests/storage/test_directory.py
+++ b/tests/storage/test_directory.py
@@ -14,12 +14,12 @@
 # limitations under the License.
 
 
-from tests import unittest
 from twisted.internet import defer
 
 from synapse.storage.directory import DirectoryStore
-from synapse.types import RoomID, RoomAlias
+from synapse.types import RoomAlias, RoomID
 
+from tests import unittest
 from tests.utils import setup_test_homeserver
 
 
diff --git a/tests/storage/test_event_push_actions.py b/tests/storage/test_event_push_actions.py
index 3cbf9a78b1..8430fc7ba6 100644
--- a/tests/storage/test_event_push_actions.py
+++ b/tests/storage/test_event_push_actions.py
@@ -13,11 +13,12 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from mock import Mock
+
 from twisted.internet import defer
 
 import tests.unittest
 import tests.utils
-from mock import Mock
 
 USER_ID = "@user:example.com"
 
diff --git a/tests/storage/test_keys.py b/tests/storage/test_keys.py
index 0be790d8f8..3a3d002782 100644
--- a/tests/storage/test_keys.py
+++ b/tests/storage/test_keys.py
@@ -14,6 +14,7 @@
 # limitations under the License.
 
 import signedjson.key
+
 from twisted.internet import defer
 
 import tests.unittest
diff --git a/tests/storage/test_presence.py b/tests/storage/test_presence.py
index f5fcb611d4..3276b39504 100644
--- a/tests/storage/test_presence.py
+++ b/tests/storage/test_presence.py
@@ -14,13 +14,13 @@
 # limitations under the License.
 
 
-from tests import unittest
 from twisted.internet import defer
 
 from synapse.storage.presence import PresenceStore
 from synapse.types import UserID
 
-from tests.utils import setup_test_homeserver, MockClock
+from tests import unittest
+from tests.utils import MockClock, setup_test_homeserver
 
 
 class PresenceStoreTestCase(unittest.TestCase):
diff --git a/tests/storage/test_profile.py b/tests/storage/test_profile.py
index 423710c9c1..2c95e5e95a 100644
--- a/tests/storage/test_profile.py
+++ b/tests/storage/test_profile.py
@@ -14,12 +14,12 @@
 # limitations under the License.
 
 
-from tests import unittest
 from twisted.internet import defer
 
 from synapse.storage.profile import ProfileStore
 from synapse.types import UserID
 
+from tests import unittest
 from tests.utils import setup_test_homeserver
 
 
diff --git a/tests/storage/test_redaction.py b/tests/storage/test_redaction.py
index 888ddfaddd..475ec900c4 100644
--- a/tests/storage/test_redaction.py
+++ b/tests/storage/test_redaction.py
@@ -14,16 +14,16 @@
 # limitations under the License.
 
 
-from tests import unittest
+from mock import Mock
+
 from twisted.internet import defer
 
 from synapse.api.constants import EventTypes, Membership
-from synapse.types import UserID, RoomID
+from synapse.types import RoomID, UserID
 
+from tests import unittest
 from tests.utils import setup_test_homeserver
 
-from mock import Mock
-
 
 class RedactionTestCase(unittest.TestCase):
 
diff --git a/tests/storage/test_registration.py b/tests/storage/test_registration.py
index f863b75846..7821ea3fa3 100644
--- a/tests/storage/test_registration.py
+++ b/tests/storage/test_registration.py
@@ -14,9 +14,9 @@
 # limitations under the License.
 
 
-from tests import unittest
 from twisted.internet import defer
 
+from tests import unittest
 from tests.utils import setup_test_homeserver
 
 
diff --git a/tests/storage/test_room.py b/tests/storage/test_room.py
index ef8a4d234f..ae8ae94b6d 100644
--- a/tests/storage/test_room.py
+++ b/tests/storage/test_room.py
@@ -14,12 +14,12 @@
 # limitations under the License.
 
 
-from tests import unittest
 from twisted.internet import defer
 
 from synapse.api.constants import EventTypes
-from synapse.types import UserID, RoomID, RoomAlias
+from synapse.types import RoomAlias, RoomID, UserID
 
+from tests import unittest
 from tests.utils import setup_test_homeserver
 
 
diff --git a/tests/storage/test_roommember.py b/tests/storage/test_roommember.py
index 657b279e5d..c5fd54f67e 100644
--- a/tests/storage/test_roommember.py
+++ b/tests/storage/test_roommember.py
@@ -14,16 +14,16 @@
 # limitations under the License.
 
 
-from tests import unittest
+from mock import Mock
+
 from twisted.internet import defer
 
 from synapse.api.constants import EventTypes, Membership
-from synapse.types import UserID, RoomID
+from synapse.types import RoomID, UserID
 
+from tests import unittest
 from tests.utils import setup_test_homeserver
 
-from mock import Mock
-
 
 class RoomMemberStoreTestCase(unittest.TestCase):
 
diff --git a/tests/storage/test_user_directory.py b/tests/storage/test_user_directory.py
index 0891308f25..23fad12bca 100644
--- a/tests/storage/test_user_directory.py
+++ b/tests/storage/test_user_directory.py
@@ -17,6 +17,7 @@ from twisted.internet import defer
 
 from synapse.storage import UserDirectoryStore
 from synapse.storage.roommember import ProfileInfo
+
 from tests import unittest
 from tests.utils import setup_test_homeserver
 
diff --git a/tests/test_distributor.py b/tests/test_distributor.py
index c066381698..04a88056f1 100644
--- a/tests/test_distributor.py
+++ b/tests/test_distributor.py
@@ -13,13 +13,14 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from . import unittest
-from twisted.internet import defer
-
 from mock import Mock, patch
 
+from twisted.internet import defer
+
 from synapse.util.distributor import Distributor
 
+from . import unittest
+
 
 class DistributorTestCase(unittest.TestCase):
 
diff --git a/tests/test_dns.py b/tests/test_dns.py
index 3b360a0fc7..b647d92697 100644
--- a/tests/test_dns.py
+++ b/tests/test_dns.py
@@ -13,16 +13,17 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from . import unittest
+from mock import Mock
+
 from twisted.internet import defer
 from twisted.names import dns, error
 
-from mock import Mock
-
 from synapse.http.endpoint import resolve_service
 
 from tests.utils import MockClock
 
+from . import unittest
+
 
 @unittest.DEBUG
 class DnsTestCase(unittest.TestCase):
diff --git a/tests/test_event_auth.py b/tests/test_event_auth.py
index d08e19c53a..06112430e5 100644
--- a/tests/test_event_auth.py
+++ b/tests/test_event_auth.py
@@ -13,10 +13,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import unittest
+
 from synapse import event_auth
 from synapse.api.errors import AuthError
 from synapse.events import FrozenEvent
-import unittest
 
 
 class EventAuthTestCase(unittest.TestCase):
diff --git a/tests/test_federation.py b/tests/test_federation.py
index fc80a69369..159a136971 100644
--- a/tests/test_federation.py
+++ b/tests/test_federation.py
@@ -1,15 +1,15 @@
 
-from twisted.internet.defer import succeed, maybeDeferred
-
-from synapse.util import Clock
-from synapse.events import FrozenEvent
-from synapse.types import Requester, UserID
-
-from tests import unittest
-from tests.server import setup_test_homeserver, ThreadedMemoryReactorClock
-
 from mock import Mock
 
+from twisted.internet.defer import maybeDeferred, succeed
+
+from synapse.events import FrozenEvent
+from synapse.types import Requester, UserID
+from synapse.util import Clock
+
+from tests import unittest
+from tests.server import ThreadedMemoryReactorClock, setup_test_homeserver
+
 
 class MessageAcceptTests(unittest.TestCase):
     def setUp(self):
diff --git a/tests/test_preview.py b/tests/test_preview.py
index 5bd36c74aa..446843367e 100644
--- a/tests/test_preview.py
+++ b/tests/test_preview.py
@@ -13,12 +13,13 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from . import unittest
-
 from synapse.rest.media.v1.preview_url_resource import (
-    summarize_paragraphs, decode_and_calc_og
+    decode_and_calc_og,
+    summarize_paragraphs,
 )
 
+from . import unittest
+
 
 class PreviewTestCase(unittest.TestCase):
 
diff --git a/tests/test_server.py b/tests/test_server.py
index 8ad822c43b..4192013f6d 100644
--- a/tests/test_server.py
+++ b/tests/test_server.py
@@ -4,9 +4,10 @@ import re
 from twisted.internet.defer import Deferred
 from twisted.test.proto_helpers import MemoryReactorClock
 
-from synapse.util import Clock
 from synapse.api.errors import Codes, SynapseError
 from synapse.http.server import JsonResource
+from synapse.util import Clock
+
 from tests import unittest
 from tests.server import make_request, setup_test_homeserver
 
diff --git a/tests/test_state.py b/tests/test_state.py
index 71c412faf4..c0f2d1152d 100644
--- a/tests/test_state.py
+++ b/tests/test_state.py
@@ -13,18 +13,18 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from tests import unittest
-from twisted.internet import defer
-
-from synapse.events import FrozenEvent
-from synapse.api.auth import Auth
-from synapse.api.constants import EventTypes, Membership
-from synapse.state import StateHandler, StateResolutionHandler
-
-from .utils import MockClock
-
 from mock import Mock
 
+from twisted.internet import defer
+
+from synapse.api.auth import Auth
+from synapse.api.constants import EventTypes, Membership
+from synapse.events import FrozenEvent
+from synapse.state import StateHandler, StateResolutionHandler
+
+from tests import unittest
+
+from .utils import MockClock
 
 _next_event_id = 1000
 
diff --git a/tests/test_test_utils.py b/tests/test_test_utils.py
index d28bb726bb..bc97c12245 100644
--- a/tests/test_test_utils.py
+++ b/tests/test_test_utils.py
@@ -14,7 +14,6 @@
 # limitations under the License.
 
 from tests import unittest
-
 from tests.utils import MockClock
 
 
diff --git a/tests/test_types.py b/tests/test_types.py
index 115def2287..729bd676c1 100644
--- a/tests/test_types.py
+++ b/tests/test_types.py
@@ -13,11 +13,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from tests import unittest
-
 from synapse.api.errors import SynapseError
 from synapse.server import HomeServer
-from synapse.types import UserID, RoomAlias, GroupID
+from synapse.types import GroupID, RoomAlias, UserID
+
+from tests import unittest
 
 mock_homeserver = HomeServer(hostname="my.domain")
 
diff --git a/tests/util/caches/test_descriptors.py b/tests/util/caches/test_descriptors.py
index a94d566c96..8176a7dabd 100644
--- a/tests/util/caches/test_descriptors.py
+++ b/tests/util/caches/test_descriptors.py
@@ -13,14 +13,17 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-from functools import partial
 import logging
+from functools import partial
 
 import mock
+
+from twisted.internet import defer, reactor
+
 from synapse.api.errors import SynapseError
 from synapse.util import logcontext
-from twisted.internet import defer, reactor
 from synapse.util.caches import descriptors
+
 from tests import unittest
 
 logger = logging.getLogger(__name__)
diff --git a/tests/util/test_dict_cache.py b/tests/util/test_dict_cache.py
index 543ac5bed9..26f2fa5800 100644
--- a/tests/util/test_dict_cache.py
+++ b/tests/util/test_dict_cache.py
@@ -14,10 +14,10 @@
 # limitations under the License.
 
 
-from tests import unittest
-
 from synapse.util.caches.dictionary_cache import DictionaryCache
 
+from tests import unittest
+
 
 class DictCacheTestCase(unittest.TestCase):
 
diff --git a/tests/util/test_expiring_cache.py b/tests/util/test_expiring_cache.py
index 31d24adb8b..d12b5e838b 100644
--- a/tests/util/test_expiring_cache.py
+++ b/tests/util/test_expiring_cache.py
@@ -14,12 +14,12 @@
 # limitations under the License.
 
 
-from .. import unittest
-
 from synapse.util.caches.expiringcache import ExpiringCache
 
 from tests.utils import MockClock
 
+from .. import unittest
+
 
 class ExpiringCacheTestCase(unittest.TestCase):
 
diff --git a/tests/util/test_file_consumer.py b/tests/util/test_file_consumer.py
index c2aae8f54c..7ce5f8c258 100644
--- a/tests/util/test_file_consumer.py
+++ b/tests/util/test_file_consumer.py
@@ -14,15 +14,16 @@
 # limitations under the License.
 
 
-from twisted.internet import defer, reactor
+import threading
+
 from mock import NonCallableMock
+from six import StringIO
+
+from twisted.internet import defer, reactor
 
 from synapse.util.file_consumer import BackgroundFileConsumer
 
 from tests import unittest
-from six import StringIO
-
-import threading
 
 
 class FileConsumerTests(unittest.TestCase):
diff --git a/tests/util/test_limiter.py b/tests/util/test_limiter.py
index 9c795d9fdb..a5a767b1ff 100644
--- a/tests/util/test_limiter.py
+++ b/tests/util/test_limiter.py
@@ -14,12 +14,12 @@
 # limitations under the License.
 
 
-from tests import unittest
-
 from twisted.internet import defer
 
 from synapse.util.async import Limiter
 
+from tests import unittest
+
 
 class LimiterTestCase(unittest.TestCase):
 
diff --git a/tests/util/test_linearizer.py b/tests/util/test_linearizer.py
index bf7e3aa885..c95907b32c 100644
--- a/tests/util/test_linearizer.py
+++ b/tests/util/test_linearizer.py
@@ -13,13 +13,14 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from synapse.util import logcontext, Clock
-from tests import unittest
+from six.moves import range
 
 from twisted.internet import defer, reactor
 
+from synapse.util import Clock, logcontext
 from synapse.util.async import Linearizer
-from six.moves import range
+
+from tests import unittest
 
 
 class LinearizerTestCase(unittest.TestCase):
diff --git a/tests/util/test_logcontext.py b/tests/util/test_logcontext.py
index 9cf90fcfc4..c54001f7a4 100644
--- a/tests/util/test_logcontext.py
+++ b/tests/util/test_logcontext.py
@@ -1,11 +1,11 @@
 import twisted.python.failure
-from twisted.internet import defer
-from twisted.internet import reactor
-from .. import unittest
+from twisted.internet import defer, reactor
 
-from synapse.util import logcontext, Clock
+from synapse.util import Clock, logcontext
 from synapse.util.logcontext import LoggingContext
 
+from .. import unittest
+
 
 class LoggingContextTestCase(unittest.TestCase):
 
diff --git a/tests/util/test_logformatter.py b/tests/util/test_logformatter.py
index 1a1a8412f2..297aebbfbe 100644
--- a/tests/util/test_logformatter.py
+++ b/tests/util/test_logformatter.py
@@ -15,6 +15,7 @@
 import sys
 
 from synapse.util.logformatter import LogFormatter
+
 from tests import unittest
 
 
diff --git a/tests/util/test_lrucache.py b/tests/util/test_lrucache.py
index dfb78cb8bd..9b36ef4482 100644
--- a/tests/util/test_lrucache.py
+++ b/tests/util/test_lrucache.py
@@ -14,12 +14,12 @@
 # limitations under the License.
 
 
-from .. import unittest
+from mock import Mock
 
 from synapse.util.caches.lrucache import LruCache
 from synapse.util.caches.treecache import TreeCache
 
-from mock import Mock
+from .. import unittest
 
 
 class LruCacheTestCase(unittest.TestCase):
diff --git a/tests/util/test_rwlock.py b/tests/util/test_rwlock.py
index 1d745ae1a7..24194e3b25 100644
--- a/tests/util/test_rwlock.py
+++ b/tests/util/test_rwlock.py
@@ -14,10 +14,10 @@
 # limitations under the License.
 
 
-from tests import unittest
-
 from synapse.util.async import ReadWriteLock
 
+from tests import unittest
+
 
 class ReadWriteLockTestCase(unittest.TestCase):
 
diff --git a/tests/util/test_snapshot_cache.py b/tests/util/test_snapshot_cache.py
index d3a8630c2f..0f5b32fcc0 100644
--- a/tests/util/test_snapshot_cache.py
+++ b/tests/util/test_snapshot_cache.py
@@ -14,10 +14,11 @@
 # limitations under the License.
 
 
-from .. import unittest
+from twisted.internet.defer import Deferred
 
 from synapse.util.caches.snapshot_cache import SnapshotCache
-from twisted.internet.defer import Deferred
+
+from .. import unittest
 
 
 class SnapshotCacheTestCase(unittest.TestCase):
diff --git a/tests/util/test_stream_change_cache.py b/tests/util/test_stream_change_cache.py
index 67ece166c7..e3897c0d19 100644
--- a/tests/util/test_stream_change_cache.py
+++ b/tests/util/test_stream_change_cache.py
@@ -1,8 +1,9 @@
-from tests import unittest
 from mock import patch
 
 from synapse.util.caches.stream_change_cache import StreamChangeCache
 
+from tests import unittest
+
 
 class StreamChangeCacheTests(unittest.TestCase):
     """
diff --git a/tests/util/test_treecache.py b/tests/util/test_treecache.py
index 7ab578a185..a5f2261208 100644
--- a/tests/util/test_treecache.py
+++ b/tests/util/test_treecache.py
@@ -14,10 +14,10 @@
 # limitations under the License.
 
 
-from .. import unittest
-
 from synapse.util.caches.treecache import TreeCache
 
+from .. import unittest
+
 
 class TreeCacheTestCase(unittest.TestCase):
     def test_get_set_onelevel(self):
diff --git a/tests/util/test_wheel_timer.py b/tests/util/test_wheel_timer.py
index fdb24a48b0..03201a4d9b 100644
--- a/tests/util/test_wheel_timer.py
+++ b/tests/util/test_wheel_timer.py
@@ -13,10 +13,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from .. import unittest
-
 from synapse.util.wheel_timer import WheelTimer
 
+from .. import unittest
+
 
 class WheelTimerTestCase(unittest.TestCase):
     def test_single_insert_fetch(self):
diff --git a/tests/utils.py b/tests/utils.py
index 189fd2711c..6adbdbfca1 100644
--- a/tests/utils.py
+++ b/tests/utils.py
@@ -15,9 +15,10 @@
 
 import hashlib
 from inspect import getcallargs
-from six.moves.urllib import parse as urlparse
 
 from mock import Mock, patch
+from six.moves.urllib import parse as urlparse
+
 from twisted.internet import defer, reactor
 
 from synapse.api.errors import CodeMessageException, cs_error