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cb562d73aa
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.
104 lines
3.4 KiB
Python
104 lines
3.4 KiB
Python
#
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# This file is licensed under the Affero General Public License (AGPL) version 3.
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#
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# Copyright 2023 The Matrix.org Foundation C.I.C.
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# Copyright (C) 2023 New Vector, Ltd
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#
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU Affero General Public License as
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# published by the Free Software Foundation, either version 3 of the
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# License, or (at your option) any later version.
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#
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# See the GNU Affero General Public License for more details:
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# <https://www.gnu.org/licenses/agpl-3.0.html>.
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#
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# Originally licensed under the Apache License, Version 2.0:
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# <http://www.apache.org/licenses/LICENSE-2.0>.
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#
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# [This file includes modifications made by New Vector Limited]
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#
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#
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from twisted.internet import defer
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from twisted.test.proto_helpers import MemoryReactor
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from synapse.server import HomeServer
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from synapse.util import Clock
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from tests import unittest
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from tests.replication._base import BaseMultiWorkerStreamTestCase
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from tests.utils import test_timeout
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class WorkerLockTestCase(unittest.HomeserverTestCase):
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def prepare(
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self, reactor: MemoryReactor, clock: Clock, homeserver: HomeServer
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) -> None:
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self.worker_lock_handler = self.hs.get_worker_locks_handler()
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def test_wait_for_lock_locally(self) -> None:
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"""Test waiting for a lock on a single worker"""
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lock1 = self.worker_lock_handler.acquire_lock("name", "key")
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self.get_success(lock1.__aenter__())
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lock2 = self.worker_lock_handler.acquire_lock("name", "key")
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d2 = defer.ensureDeferred(lock2.__aenter__())
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self.assertNoResult(d2)
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self.get_success(lock1.__aexit__(None, None, None))
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self.get_success(d2)
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self.get_success(lock2.__aexit__(None, None, None))
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def test_lock_contention(self) -> None:
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"""Test lock contention when a lot of locks wait on a single worker"""
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# It takes around 0.5s on a 5+ years old laptop
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with test_timeout(5):
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nb_locks = 500
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d = self._take_locks(nb_locks)
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self.assertEqual(self.get_success(d), nb_locks)
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async def _take_locks(self, nb_locks: int) -> int:
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locks = [
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self.hs.get_worker_locks_handler().acquire_lock("test_lock", "")
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for _ in range(nb_locks)
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]
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nb_locks_taken = 0
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for lock in locks:
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async with lock:
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nb_locks_taken += 1
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return nb_locks_taken
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class WorkerLockWorkersTestCase(BaseMultiWorkerStreamTestCase):
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def prepare(
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self, reactor: MemoryReactor, clock: Clock, homeserver: HomeServer
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) -> None:
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self.main_worker_lock_handler = self.hs.get_worker_locks_handler()
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def test_wait_for_lock_worker(self) -> None:
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"""Test waiting for a lock on another worker"""
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worker = self.make_worker_hs(
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"synapse.app.generic_worker",
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extra_config={
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"redis": {"enabled": True},
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},
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)
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worker_lock_handler = worker.get_worker_locks_handler()
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lock1 = self.main_worker_lock_handler.acquire_lock("name", "key")
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self.get_success(lock1.__aenter__())
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lock2 = worker_lock_handler.acquire_lock("name", "key")
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d2 = defer.ensureDeferred(lock2.__aenter__())
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self.assertNoResult(d2)
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self.get_success(lock1.__aexit__(None, None, None))
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self.get_success(d2)
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self.get_success(lock2.__aexit__(None, None, None))
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