STINNER Victor added the comment: The race condition occurs when _WaitHandleFuture().cancel() is called. This object is created by IocpProactor.wait_for_handle().
_WaitHandleFuture().cancel() is only called by 4 tests: - test_cancel_post_init() - test_cancel_make_subprocess_transport_exec - test_wait_for_handle - test_wait_for_handle_cancel It looks like the "GetQueuedCompletionStatus() returned an unexpected event" error is logged when test_wait_for_handle() and/or test_wait_for_handle_cancel() is executed(). Disabling these tests is enough to workaround this issue. Using Tulip, use "python3 runtests.py -r" to reproduce the issue. You may have to run this command multiple times to see the error, the bug is random. ---------- _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue23095> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com