https://github.com/python/cpython/commit/e152a82bf3bd68c5bb0831bd78901943c085e7f0 commit: e152a82bf3bd68c5bb0831bd78901943c085e7f0 branch: 3.14 author: Miss Islington (bot) <[email protected]> committer: vsajip <[email protected]> date: 2026-10-21T07:36:07+01:00 summary:
[3.14] gh-159690: Fix timed log rotation after a failed or duplicate rollover (GH-159692) (GH-160025) (cherry picked from commit b12497756ba0242a2a389dd1bb6fb26ddbd48602) Co-authored-by: Pengyu Lee <[email protected]> files: A Misc/NEWS.d/next/Library/2026-10-20-00-12-05.gh-issue-159690.vZgLP6.rst M Lib/logging/handlers.py M Lib/test/test_logging.py diff --git a/Lib/logging/handlers.py b/Lib/logging/handlers.py index 1776358a9788040..0a787f4d3a93a7e 100644 --- a/Lib/logging/handlers.py +++ b/Lib/logging/handlers.py @@ -446,6 +446,7 @@ def doRollover(self): timeTuple = time.localtime(t + addend) dfn = self.rotation_filename(self.baseFilename + "." + time.strftime(self.suffix, timeTuple)) + self.rolloverAt = self.computeRollover(currentTime) if os.path.exists(dfn): # Already rolled over. return @@ -459,7 +460,6 @@ def doRollover(self): os.remove(s) if not self.delay: self.stream = self._open() - self.rolloverAt = self.computeRollover(currentTime) class WatchedFileHandler(logging.FileHandler): """ diff --git a/Lib/test/test_logging.py b/Lib/test/test_logging.py index bca306877008cd0..4b3473835b133f8 100644 --- a/Lib/test/test_logging.py +++ b/Lib/test/test_logging.py @@ -6683,6 +6683,75 @@ def test_rollover_at_midnight(self, weekly=False): def test_rollover_at_weekday(self): self.test_rollover_at_midnight(weekly=True) + def _make_fake_time_handler(self, now, when='S', **kwargs): + dirname = tempfile.mkdtemp() + self.addCleanup(os_helper.rmtree, dirname) + fn = os.path.join(dirname, 'test.log') + with patch('time.time', lambda: now[0]): + fh = logging.handlers.TimedRotatingFileHandler( + fn, when=when, encoding='utf-8', delay=True, **kwargs) + self.addCleanup(fh.close) + return fh + + def test_rollover_after_failed_rollover(self): + for target in 'os.remove', '_open': + with self.subTest(target=target): + now = [1_000_000_000] + fh = self._make_fake_time_handler(now, backupCount=1) + fn = fh.baseFilename + emit = lambda msg: fh.emit(logging.makeLogRecord({'msg': msg})) + with patch('time.time', lambda: now[0]): + for msg in 'a', 'b': + now[0] += 2 + emit(msg) + now[0] += 2 + if target == '_open': + failure = patch.object(fh, '_open', side_effect=OSError) + fh.delay = False + else: + failure = patch('os.remove', side_effect=OSError) + with failure as failed, support.captured_stderr(): + emit('c') + failed.assert_called_once() + self.assertGreater(fh.rolloverAt, now[0]) + fh.delay = True + for msg in 'd', 'e': + now[0] += 2 + emit(msg) + fh.close() + with open(fn, encoding='utf-8') as f: + self.assertEqual(f.read(), 'e\n') + backups = [f for f in os.listdir(os.path.dirname(fn)) + if f != 'test.log'] + self.assertEqual(len(backups), 1) + + def test_rollover_existing_backup(self): + now = [1_000_000_000] + fh = self._make_fake_time_handler(now) + fn = fh.baseFilename + with patch('time.time', lambda: now[0]): + fh.emit(logging.makeLogRecord({'msg': 'a'})) + t = fh.rolloverAt - fh.interval + dfn = fh.rotation_filename( + fn + '.' + time.strftime(fh.suffix, time.localtime(t))) + with open(dfn, 'w', encoding='utf-8') as f: + f.write('existing\n') + now[0] += 2 + fh.emit(logging.makeLogRecord({'msg': 'b'})) + self.assertGreater(fh.rolloverAt, now[0]) + t = fh.rolloverAt - fh.interval + next_dfn = fh.rotation_filename( + fn + '.' + time.strftime(fh.suffix, time.localtime(t))) + now[0] += 2 + fh.emit(logging.makeLogRecord({'msg': 'c'})) + fh.close() + with open(dfn, encoding='utf-8') as f: + self.assertEqual(f.read(), 'existing\n') + with open(next_dfn, encoding='utf-8') as f: + self.assertEqual(f.read(), 'a\nb\n') + with open(fn, encoding='utf-8') as f: + self.assertEqual(f.read(), 'c\n') + def test_invalid(self): assertRaises = self.assertRaises assertRaises(ValueError, logging.handlers.TimedRotatingFileHandler, diff --git a/Misc/NEWS.d/next/Library/2026-10-20-00-12-05.gh-issue-159690.vZgLP6.rst b/Misc/NEWS.d/next/Library/2026-10-20-00-12-05.gh-issue-159690.vZgLP6.rst new file mode 100644 index 000000000000000..b94d79501b9abed --- /dev/null +++ b/Misc/NEWS.d/next/Library/2026-10-20-00-12-05.gh-issue-159690.vZgLP6.rst @@ -0,0 +1,3 @@ +Fix :class:`logging.handlers.TimedRotatingFileHandler` permanently stopping +rollover after a rollover failed or its backup file already existed, for +example at a DST change. _______________________________________________ Python-checkins mailing list -- [email protected] To unsubscribe send an email to [email protected] https://mail.python.org/mailman3//lists/python-checkins.python.org Member address: [email protected]
