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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"test_multiprocessing_fork: test_nested_startmethod() fails randomly.","articleBody":"test_nested_startmethod() fails randomly. Since there is no synchronization, putting items in the queue is not really ordered.\r\n\r\nI suggest to either accept [1, 2] and [2, 1] in the test, or add some kind of synchronization to ensure that events happen in the expected order. Here I don't think that order matters.\r\n\r\nThe test was added by PR #108568 of issue gh-108520.\r\n\r\n```\r\nFAIL: test_nested_startmethod (test.test_multiprocessing_fork.test_misc.TestStartMethod.test_nested_startmethod)\r\n----------------------------------------------------------------------\r\nTraceback (most recent call last):\r\n  File \"/home/buildbot/buildarea/3.x.cstratak-RHEL7-ppc64le.lto/build/Lib/test/_test_multiprocessing.py\", line 5475, in test_nested_startmethod\r\n    self.assertEqual(results, [2, 1])\r\nAssertionError: Lists differ: [1, 2] != [2, 1]\r\n\r\nFirst differing element 0:\r\n1\r\n2\r\n\r\n- [1, 2]\r\n+ [2, 1]\r\n```\r\n\r\nbuild: https://buildbot.python.org/all/#/builders/503/builds/3941\r\n\r\nThe failure can be reproduced by stressing the test:\r\n\r\n```\r\n$ ./python -m test test_multiprocessing_fork.test_misc -m test_nested_startmethod -v -j50 --forever\r\n(...)\r\n0:00:24 load avg: 20.03 [157/1] test_multiprocessing_fork.test_misc failed (1 failure)\r\ntest_nested_startmethod (test.test_multiprocessing_fork.test_misc.TestStartMethod.test_nested_startmethod) ... FAIL\r\n\r\n======================================================================\r\nFAIL: test_nested_startmethod (test.test_multiprocessing_fork.test_misc.TestStartMethod.test_nested_startmethod)\r\n----------------------------------------------------------------------\r\nTraceback (most recent call last):\r\n  File \"/home/vstinner/python/3.11/Lib/test/_test_multiprocessing.py\", line 5399, in test_nested_startmethod\r\n    self.assertEqual(results, [2, 1])\r\nAssertionError: Lists differ: [1, 2] != [2, 1]\r\n\r\nFirst differing element 0:\r\n1\r\n2\r\n\r\n- [1, 2]\r\n+ [2, 1]\r\n\r\n----------------------------------------------------------------------\r\nRan 1 test in 2.150s\r\n\r\nFAILED (failures=1)\r\ntest test_multiprocessing_fork.test_misc failed\r\n```\n\n\u003c!-- gh-linked-prs --\u003e\n### Linked PRs\n* gh-109707\n* gh-109762\n* gh-109763\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/vstinner","@type":"Person","name":"vstinner"},"datePublished":"2023-09-22T01:24:51.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/109706/cpython/issues/109706"}