ee3f73a133
The fasteners lib in version 0.15.0 removed the
threading.current_thread workaround for eventlet[1] because eventlet
seemed to fixed the current_thread issues tracked in [2]. However the
fix for [2] only fixed half of the problem. The threading.current_thread
call works if it is called from thread created by eventlet.spawn.
However if the thread is created with eventlet.spawn_n then
threading.current_thread is still broken and returns the ID of the
python native thread.
The fasteners' ReaderWriterLock depends heavily on
threading.current_thread to decide which thread holds a lock and to
allow re-entry of that thread. This leads to the situation that
multiple threads created from spawn_n could take the same
ReaderWriterLock at the same time.
The fair internal lock in oslo.concurrency uses ReaderWriterLock and
as a result such lock is broken for threads created with spawn_n.
Note that this issue was raised with eventlet in [3] when the nova team
detected it via a direct usage of ReaderWriterLock in the nova test
code. As [3] did not lead to a solution in eventlet nova implemented a
nova local fix for the test code in [4].
However now we detected that oslo.concurrency is affected by this issue
as well.
This patch restores the workaround that was removed by [1].
Note that a fasteners issue [5] also opened to restore the
workaround[1].
[1] 467ed75ee1
[2] https://github.com/eventlet/eventlet/issues/172
[3] https://github.com/eventlet/eventlet/issues/731
[4] https://review.opendev.org/c/openstack/nova/+/813114
[5] https://github.com/harlowja/fasteners/issues/96
Closes-Bug: #1988311
Change-Id: Ia873bcc6b07121c9bd0b94c593567d537b4c1112
105 lines
3.3 KiB
Python
105 lines
3.3 KiB
Python
# Copyright 2011 Justin Santa Barbara
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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import os
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import tempfile
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import eventlet
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from eventlet import greenpool
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from oslotest import base as test_base
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from oslo_concurrency import lockutils
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class TestFileLocks(test_base.BaseTestCase):
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def test_concurrent_green_lock_succeeds(self):
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"""Verify spawn_n greenthreads with two locks run concurrently."""
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tmpdir = tempfile.mkdtemp()
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self.completed = False
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def locka(wait):
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a = lockutils.InterProcessLock(os.path.join(tmpdir, 'a'))
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with a:
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wait.wait()
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self.completed = True
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def lockb(wait):
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b = lockutils.InterProcessLock(os.path.join(tmpdir, 'b'))
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with b:
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wait.wait()
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wait1 = eventlet.event.Event()
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wait2 = eventlet.event.Event()
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pool = greenpool.GreenPool()
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pool.spawn_n(locka, wait1)
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pool.spawn_n(lockb, wait2)
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wait2.send()
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eventlet.sleep(0)
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wait1.send()
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pool.waitall()
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self.assertTrue(self.completed)
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class TestInternalLock(test_base.BaseTestCase):
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def _test_internal_lock_with_two_threads(self, fair, spawn):
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self.other_started = eventlet.event.Event()
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self.other_finished = eventlet.event.Event()
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def other():
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self.other_started.send('started')
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with lockutils.lock("my-lock", fair=fair):
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pass
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self.other_finished.send('finished')
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with lockutils.lock("my-lock", fair=fair):
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# holding the lock and starting another thread that also wants to
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# take it before finishes
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spawn(other)
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# let the other thread start
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self.other_started.wait()
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eventlet.sleep(0)
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# the other thread should not have finished as it would need the
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# lock we are holding
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self.assertIsNone(
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self.other_finished.wait(0.5),
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"Two threads was able to take the same lock",
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)
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# we released the lock, let the other thread take it and run to
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# completion
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result = self.other_finished.wait()
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self.assertEqual('finished', result)
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def test_lock_with_spawn(self):
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self._test_internal_lock_with_two_threads(
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fair=False, spawn=eventlet.spawn
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)
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def test_lock_with_spawn_n(self):
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self._test_internal_lock_with_two_threads(
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fair=False, spawn=eventlet.spawn_n
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)
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def test_fair_lock_with_spawn(self):
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self._test_internal_lock_with_two_threads(
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fair=True, spawn=eventlet.spawn
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)
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def test_fair_lock_with_spawn_n(self):
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self._test_internal_lock_with_two_threads(
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fair=True, spawn=eventlet.spawn_n
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)
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