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oslo.concurrency
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OpenStack library for all concurrency-related code
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Balazs Gibizer ee3f73a133 Fix fair internal lock used from eventlet.spawn_n 
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
 		2022-09-05 13:29:04 +02:00
doc Remove unnecessary unicode prefixes 2022-04-19 19:39:35 +08:00
oslo_concurrency Fix fair internal lock used from eventlet.spawn_n 2022-09-05 13:29:04 +02:00
releasenotes Merge "Fix formatting of release list" 2022-07-14 11:56:56 +00:00
.coveragerc Fix coverage configuration and execution 2015-10-05 17:01:16 -04:00
.gitignore ignore reno builds artifacts 2020-02-11 15:25:49 +01:00
.gitreview OpenDev Migration Patch 2019-04-19 19:28:07 +00:00
.mailmap exported from oslo-incubator by graduate.sh 2014-08-07 22:26:50 +04:00
.pre-commit-config.yaml Move flake8 as a pre-commit local target. 2021-03-23 13:15:24 +01:00
.stestr.conf Switch to stestr 2018-07-04 08:18:31 +07:00
.zuul.yaml Update CI to use unversioned jobs template 2022-03-15 15:07:07 +00:00
CONTRIBUTING.rst Align contributing doc with oslo's policy 2020-05-04 18:20:24 +02:00
HACKING.rst Update URLs in documents according to document migration 2017-07-12 22:22:54 +08:00
LICENSE exported from oslo-incubator by graduate.sh 2014-08-07 22:26:50 +04:00
README.rst Replace git.openstack.org URLs with opendev.org URLs 2019-05-05 13:01:11 +08:00
requirements.txt Remove six usage 2020-05-09 16:42:30 +02:00
setup.cfg Drop python3.6/3.7 support in testing runtime 2022-05-05 16:10:49 +02:00
setup.py remove outdated header 2020-02-10 18:34:51 +01:00
test-requirements.txt Adding pre-commit 2020-09-03 14:25:24 +02:00
tox.ini Prove that spawn_n with fair lock is broken 2022-09-05 13:27:37 +02:00

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oslo.concurrency

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The oslo.concurrency library has utilities for safely running multi-thread, multi-process applications using locking mechanisms and for running external processes.