test_logging: rotation tests fails on Windows, macOS and FreeBSD

[vstinner]

Bug report

• Windows PGO TailCall: https://buildbot.python.org/#/builders/1872/builds/84
• macOS NoGIL: https://buildbot.python.org/#/builders/1367/builds/1140
• FreeBSD14 Refleaks: https://buildbot.python.org/#/builders/1617/builds/886

Example on macOS:

FAIL: test_rollover_based_on_st_birthtime_only (test.test_logging.TimedRotatingFileHandlerTest.test_rollover_based_on_st_birthtime_only)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/buildbot/buildarea/pull_request.itamaro-macos-arm64-aws.macos-with-brew.refleak.nogil/build/Lib/test/test_logging.py", line 6666, in test_rollover_based_on_st_birthtime_only
    self.assertTrue(found, msg=msg)
    ~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^
AssertionError: False is not true : No rotated files found, went back 5 seconds

Example on Windows:

FAIL: test_rollover_based_on_st_birthtime_only (test.test_logging.TimedRotatingFileHandlerTest.test_rollover_based_on_st_birthtime_only)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "C:\bbarea\pull_request.itamaro-win64-srv-22-aws.tailcall.pgo\build\Lib\test\test_logging.py", line 6666, in test_rollover_based_on_st_birthtime_only
    self.assertTrue(found, msg=msg)
    ~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^
AssertionError: False is not true : No rotated files found, went back 5 seconds

Stdout:
Contents of test_logging-2-njcaf5hh.log:
os.stat_result(st_mode=33206, st_ino=116249165381905831, st_dev=5772745545947373322, st_nlink=1, st_uid=0, st_gid=0, st_size=88, st_atime=1780658874, st_mtime=1780658874, st_ctime=1780658869)
2026-06-05 11:27:54,029 testing - new record supposedly in the new file after rollover

Contents of test_logging-2-njcaf5hh.log.2026-06-05_11-27-49:
os.stat_result(st_mode=33206, st_ino=167477611143228771, st_dev=5772745545947373322, st_nlink=1, st_uid=0, st_gid=0, st_size=123, st_atime=1780658871, st_mtime=1780658871, st_ctime=1780658869)
2026-06-05 11:27:49,817 testing - initial
2026-06-05 11:27:51,921 testing - update before rollover to renew the st_mtime


Stderr:
Test time: 2026-06-05 11-27-54
The only matching files are: ['test_logging-2-njcaf5hh.log', 'test_logging-2-njcaf5hh.log.2026-06-05_11-27-49']

[sergey-miryanov]

@serhiy-storchaka working on this too #84649 (comment)

[vstinner]

It seems like the test_logging regression was introduced by the change commit ac3694b:

commit ac3694b008e4f9d5d5ea6ff8584078f92f6906ab
Author: Ivan Marton <github@martonivan.hu>
Date:   Thu Jun 4 15:50:33 2026 +0200

    gh-84649: Make TimedRotatingFileHandler use CTIME instead of MTIME (GH-24660)
    
    The TimedRotatingFileHandler previously only used st_mtime attribute of the
    log file to detect whether it has to be rotate yet or not. In cases when the
    file is changed within the rotatation period the st_mtime is also updated
    to the current time and the rotation never happens.
    
    It's more appropriate to check the file creation time (st_ctime) instead.
    Whenever available, the more appropriate st_birthtime will be in use. (This
    feature is available on FreeBSD, MacOS and Windows at the moment.) If
    the st_mtime would be newer than st_ctime (e.g.: because the inode
    related to the file has been changed without any file content
    modification), then the earliest attribute will be used.

[vstinner]

The test fails randomly. python -m test -v test_logging -m test_rollover_based_on_st_birthtime_only -F can be used to reproduce the bug (it may take a few iterations before hitting the bug).

[serhiy-storchaka]

#150954 fixes it. Before it, the test failed after 5-10 iterations, with it, it did not fail after more than a hundred.

[vstinner]

#150954 fixes it. Before it, the test failed after 5-10 iterations, with it, it did not fail after more than a hundred.

I confirm that I fail to reproduce the issue after 1000 iterations of python -m test -v test_logging -m test_rollover_based_on_st_birthtime_only -F on Windows and FreeBSD.