From 0a81038ea0e308d2944b7deae43060e4982b0abe Mon Sep 17 00:00:00 2001 From: Erik Johnston Date: Fri, 14 Sep 2018 14:39:59 +0100 Subject: [PATCH] Add in flight real time metrics for Measure blocks --- synapse/metrics/__init__.py | 110 +++++++++++++++++++++++++++++++++++- synapse/util/metrics.py | 22 ++++++++ 2 files changed, 131 insertions(+), 1 deletion(-) diff --git a/synapse/metrics/__init__.py b/synapse/metrics/__init__.py index 550f8443f..98333b204 100644 --- a/synapse/metrics/__init__.py +++ b/synapse/metrics/__init__.py @@ -18,8 +18,11 @@ import gc import logging import os import platform +import threading import time +import six + import attr from prometheus_client import Counter, Gauge, Histogram from prometheus_client.core import REGISTRY, GaugeMetricFamily @@ -68,7 +71,7 @@ class LaterGauge(object): return if isinstance(calls, dict): - for k, v in calls.items(): + for k, v in six.iteritems(calls): g.add_metric(k, v) else: g.add_metric([], calls) @@ -87,6 +90,111 @@ class LaterGauge(object): all_gauges[self.name] = self +class InFlightGauge(object): + """Tracks number of things (e.g. requests, Measure blocks, etc) in flight + at any given time. + + Each InFlightGauge will create a metric called `_total` that counts + the number of in flight blocks, as well as a metrics for each item in the + given `sub_metrics` as `_` which will get updated by the + callbacks. + + Args: + name (str) + desc (str) + labels (list[str]) + sub_metrics (list[str]): A list of sub metrics that the callbacks + will update. + """ + + # TODO: Expand this to + + def __init__(self, name, desc, labels, sub_metrics): + self.name = name + self.desc = desc + self.labels = labels + self.sub_metrics = sub_metrics + + # Create a class which have the sub_metrics values as attributes, which + # default to 0 on initialization. Used to pass to registered callbacks. + self._metrics_class = attr.make_class( + "_MetricsEntry", + attrs={x: attr.ib(0) for x in sub_metrics}, + slots=True, + ) + + # Counts number of in flight blocks for a given set of label values + self._registrations = {} + + # Protects access to _registrations + self._lock = threading.Lock() + + self._register_with_collector() + + def register(self, key, callback): + """Registers that we've entered a new block with labels `key`. + + `callback` gets called each time the metrics are collected. The same + value must also be given to `unregister`. + + `callback` gets called with an object that has an attribute per + sub_metric, which should be updated with the necessary values. Note that + the metrics object is shared between all callbacks registered with the + same key. + + Note that `callback` may be called on a separate thread. + """ + with self._lock: + self._registrations.setdefault(key, set()).add(callback) + + def unregister(self, key, callback): + """Registers that we've exited a block with labels `key`. + """ + + with self._lock: + self._registrations.setdefault(key, set()).discard(callback) + + def collect(self): + """Called by prometheus client when it reads metrics. + + Note: may be called by a separate thread. + """ + in_flight = GaugeMetricFamily(self.name + "_total", self.desc, labels=self.labels) + + metrics_by_key = {} + + # We copy so that we don't mutate the list while iterating + with self._lock: + keys = list(self._registrations) + + for key in keys: + with self._lock: + callbacks = set(self._registrations[key]) + + in_flight.add_metric(key, len(callbacks)) + + metrics = self._metrics_class() + metrics_by_key[key] = metrics + for callback in callbacks: + callback(metrics) + + yield in_flight + + for name in self.sub_metrics: + gauge = GaugeMetricFamily("_".join([self.name, name]), "", labels=self.labels) + for key, metrics in six.iteritems(metrics_by_key): + gauge.add_metric(key, getattr(metrics, name)) + yield gauge + + def _register_with_collector(self): + if self.name in all_gauges.keys(): + logger.warning("%s already registered, reregistering" % (self.name,)) + REGISTRY.unregister(all_gauges.pop(self.name)) + + REGISTRY.register(self) + all_gauges[self.name] = self + + # # Detailed CPU metrics # diff --git a/synapse/util/metrics.py b/synapse/util/metrics.py index 97f126738..4b4ac5f6c 100644 --- a/synapse/util/metrics.py +++ b/synapse/util/metrics.py @@ -20,6 +20,7 @@ from prometheus_client import Counter from twisted.internet import defer +from synapse.metrics import InFlightGauge from synapse.util.logcontext import LoggingContext logger = logging.getLogger(__name__) @@ -45,6 +46,13 @@ block_db_txn_duration = Counter( block_db_sched_duration = Counter( "synapse_util_metrics_block_db_sched_duration_seconds", "", ["block_name"]) +# Tracks the number of blocks currently active +in_flight = InFlightGauge( + "synapse_util_metrics_block_in_flight", "", + labels=["block_name"], + sub_metrics=["real_time_max", "real_time_sum"], +) + def measure_func(name): def wrapper(func): @@ -82,10 +90,14 @@ class Measure(object): self.start_usage = self.start_context.get_resource_usage() + in_flight.register((self.name,), self._update_in_flight) + def __exit__(self, exc_type, exc_val, exc_tb): if isinstance(exc_type, Exception) or not self.start_context: return + in_flight.unregister((self.name,), self._update_in_flight) + duration = self.clock.time() - self.start block_counter.labels(self.name).inc() @@ -120,3 +132,13 @@ class Measure(object): if self.created_context: self.start_context.__exit__(exc_type, exc_val, exc_tb) + + def _update_in_flight(self, metrics): + """Gets called when processing in flight metrics + """ + duration = self.clock.time() - self.start + + metrics.real_time_max = max(metrics.real_time_max, duration) + metrics.real_time_sum += duration + + # TODO: Add other in flight metrics.