oslo.concurrency/oslo_concurrency/tests/unit
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
..
__init__.py Move out of the oslo namespace package 2014-11-14 17:17:25 -05:00
test_lockutils.py Add support for non-blocking locks 2021-06-24 09:45:48 +02:00
test_lockutils_eventlet.py Fix fair internal lock used from eventlet.spawn_n 2022-09-05 13:29:04 +02:00
test_processutils.py Add support for timeout to processutils.execute 2020-06-24 10:53:21 +02:00