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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"multiprocessing.Pool: leak of global named resources using multiprocessing spawn","articleBody":"# Bug report\n\n### Bug description:\n\nI'm receiving a warning when using the `multiprocessing.Pool` in `spawn` mode.\n\n```\n/opt/pyenv/versions/3.12.4/lib/python3.12/multiprocessing/resource_tracker.py:254: UserWarning: resource_tracker: There appear to be 1 leaked semaphore objects to clean up at shutdown\n  warnings.warn('resource_tracker: There appear to be %d '\n```\n\nA similar issue was brought up and fixed before, when `multiprocessing.Process` was used:\nhttps://github.com/python/cpython/pull/30617\n\nThe test case introduced by the PR above: https://github.com/python/cpython/blob/3.12/Lib/test/_test_multiprocessing.py#L6040C7-L6040C24\n\nTo trigger the warning, I just replaced the `Process` with `Pool` as follows:\n\n```python\nimport multiprocessing as mp\nctx = mp.get_context('spawn')\nglobal_resource = ctx.Semaphore()\ndef submain(): pass\nif __name__ == '__main__':\n    p = ctx.Pool(processes=3).starmap(submain, [tuple() for i in range(5)])\n```\n\n### CPython versions tested on:\n\n3.11, 3.12, CPython main branch\n\n### Operating systems tested on:\n\nLinux","author":{"url":"https://github.com/vindex10","@type":"Person","name":"vindex10"},"datePublished":"2024-08-07T09:10:13.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":1},"url":"https://github.com/122770/cpython/issues/122770"}