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synapse/tests/handlers/test_worker_lock.py
Mathieu Velten cb562d73aa
Improve lock performance when a lot of locks are waiting (#16840)
When a lot of locks are waiting for a single lock, notifying all locks
independently with `call_later` on each release is really costly and
incurs some kind of async contention, where the CPU is spinning a lot
for not much.

The included test is taking around 30s before the change, and 0.5s
after.

It was found following failing tests with
https://github.com/element-hq/synapse/pull/16827.
2024-03-14 13:49:54 +00:00

104 lines
3.4 KiB
Python

#
# This file is licensed under the Affero General Public License (AGPL) version 3.
#
# Copyright 2023 The Matrix.org Foundation C.I.C.
# Copyright (C) 2023 New Vector, Ltd
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as
# published by the Free Software Foundation, either version 3 of the
# License, or (at your option) any later version.
#
# See the GNU Affero General Public License for more details:
# <https://www.gnu.org/licenses/agpl-3.0.html>.
#
# Originally licensed under the Apache License, Version 2.0:
# <http://www.apache.org/licenses/LICENSE-2.0>.
#
# [This file includes modifications made by New Vector Limited]
#
#
from twisted.internet import defer
from twisted.test.proto_helpers import MemoryReactor
from synapse.server import HomeServer
from synapse.util import Clock
from tests import unittest
from tests.replication._base import BaseMultiWorkerStreamTestCase
from tests.utils import test_timeout
class WorkerLockTestCase(unittest.HomeserverTestCase):
def prepare(
self, reactor: MemoryReactor, clock: Clock, homeserver: HomeServer
) -> None:
self.worker_lock_handler = self.hs.get_worker_locks_handler()
def test_wait_for_lock_locally(self) -> None:
"""Test waiting for a lock on a single worker"""
lock1 = self.worker_lock_handler.acquire_lock("name", "key")
self.get_success(lock1.__aenter__())
lock2 = self.worker_lock_handler.acquire_lock("name", "key")
d2 = defer.ensureDeferred(lock2.__aenter__())
self.assertNoResult(d2)
self.get_success(lock1.__aexit__(None, None, None))
self.get_success(d2)
self.get_success(lock2.__aexit__(None, None, None))
def test_lock_contention(self) -> None:
"""Test lock contention when a lot of locks wait on a single worker"""
# It takes around 0.5s on a 5+ years old laptop
with test_timeout(5):
nb_locks = 500
d = self._take_locks(nb_locks)
self.assertEqual(self.get_success(d), nb_locks)
async def _take_locks(self, nb_locks: int) -> int:
locks = [
self.hs.get_worker_locks_handler().acquire_lock("test_lock", "")
for _ in range(nb_locks)
]
nb_locks_taken = 0
for lock in locks:
async with lock:
nb_locks_taken += 1
return nb_locks_taken
class WorkerLockWorkersTestCase(BaseMultiWorkerStreamTestCase):
def prepare(
self, reactor: MemoryReactor, clock: Clock, homeserver: HomeServer
) -> None:
self.main_worker_lock_handler = self.hs.get_worker_locks_handler()
def test_wait_for_lock_worker(self) -> None:
"""Test waiting for a lock on another worker"""
worker = self.make_worker_hs(
"synapse.app.generic_worker",
extra_config={
"redis": {"enabled": True},
},
)
worker_lock_handler = worker.get_worker_locks_handler()
lock1 = self.main_worker_lock_handler.acquire_lock("name", "key")
self.get_success(lock1.__aenter__())
lock2 = worker_lock_handler.acquire_lock("name", "key")
d2 = defer.ensureDeferred(lock2.__aenter__())
self.assertNoResult(d2)
self.get_success(lock1.__aexit__(None, None, None))
self.get_success(d2)
self.get_success(lock2.__aexit__(None, None, None))