https://github.com/python/cpython/commit/3945eaf2fcd9cbc3f3061275bd29751c8b2e7d3b commit: 3945eaf2fcd9cbc3f3061275bd29751c8b2e7d3b branch: main author: Abhinav <[email protected]> committer: asvetlov <[email protected]> date: 2026-11-03T00:08:42+01:00 summary:
gh-158097: Make test_staggered_race_with_eager_tasks deterministic (#158469) * gh-158097: Make test_staggered_race_with_eager_tasks deterministic staggered_race() awaits the coroutines it is given inline, so the "await asyncio.sleep(0)" in the test's fail() helper suspended the run_one_coro() task running it and left a scheduled resumption behind. If the asyncio.sleep(1) winner (started 0.25s late by the stagger delay) completes before that resumption runs, the winner's cancel() sets _must_cancel and the resumption throws CancelledError into fail(), so excs[2] reports a CancelledError instead of a ValueError. Pending timers are only moved onto the ready queue at the top of BaseEventLoop._run_once() and are appended after the handles already queued, so the t=0.50s stagger timer and the t=1.25s sleep(1) timer run in due-time order. When both are due in the same _run_once() - which is what a busy CI machine causes - the stagger timer starts fail(), which immediately suspends again, and the very next handle is the winner. Raise straight away instead, so the ValueError is stored in excs[2] in the same step that starts the coroutine and there is no longer a scheduled resumption for a cancellation to overtake. The outcome no longer depends on the event loop getting another iteration. * Update Lib/test/test_asyncio/test_eager_task_factory.py * Delete Misc/NEWS.d/next/Tests/2026-09-30-00-00-00.gh-issue-158097.pcB3mO.rst --------- Co-authored-by: abhinav-phi <[email protected]> Co-authored-by: Andrew Svetlov <[email protected]> files: M Lib/test/test_asyncio/test_eager_task_factory.py diff --git a/Lib/test/test_asyncio/test_eager_task_factory.py b/Lib/test/test_asyncio/test_eager_task_factory.py index 594a48baa32e52..73496de81a58ef 100644 --- a/Lib/test/test_asyncio/test_eager_task_factory.py +++ b/Lib/test/test_asyncio/test_eager_task_factory.py @@ -217,7 +217,9 @@ def test_staggered_race_with_eager_tasks(self): # See https://github.com/python/cpython/issues/124309 async def fail(): - await asyncio.sleep(0) + # Raise without suspending: staggered_race() cancels unfinished + # coroutines once another one wins, so yielding first could turn + # this into a CancelledError when the event loop is busy. raise ValueError("no good") async def blocked(): _______________________________________________ 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]
