From a376a72bd92cd7c9930467dd1aba40045fb75e3b Mon Sep 17 00:00:00 2001 From: elfstrom Date: Tue, 3 Oct 2023 23:59:49 +0200 Subject: gh-109917: Fix test instability in test_concurrent_futures (#110306) The test had an instability issue due to the ordering of the dummy queue operation and the real wakeup pipe operations. Both primitives are thread safe but not done atomically as a single update and may interleave arbitrarily. With the old order of operations this can lead to an incorrect state where the dummy queue is full but the wakeup pipe is empty. By swapping the order in clear() I think this can no longer happen in any possible operation interleaving (famous last words). --- Lib/test/test_concurrent_futures/test_deadlock.py | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/Lib/test/test_concurrent_futures/test_deadlock.py b/Lib/test/test_concurrent_futures/test_deadlock.py index af70254..3c30c45 100644 --- a/Lib/test/test_concurrent_futures/test_deadlock.py +++ b/Lib/test/test_concurrent_futures/test_deadlock.py @@ -286,11 +286,12 @@ class ExecutorDeadlockTest: super().wakeup() def clear(self): + super().clear() try: while True: self._dummy_queue.get_nowait() except queue.Empty: - super().clear() + pass with (unittest.mock.patch.object(futures.process._ExecutorManagerThread, 'run', mock_run), -- cgit v0.12