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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Daemonic threads not killed in some circumstances in python 3.13","articleBody":"# Bug report\r\n\r\n### Bug description:\r\n\r\nI got a [bug report](https://github.com/pycompression/python-zlib-ng/issues/53) on python-zlib-ng where using the threaded opening the program would hang if an exception occurred and a context manager was not used. \r\n\r\nI fixed it by changing the threads to be daemonic: https://github.com/pycompression/python-zlib-ng/pull/54. \r\n\r\nThis fixes the issue on python 3.9, 3.10, 3.11 and 3.12, but not 3.13-rc2. Also the latest main branch is affected. Unfortunately I could not create a minimal reproducer, other than running the test directly. Daemonic threads seem not to work in this particular case, where there are some BufferedIO streams and queues involved.\r\n\r\n\r\n```\r\ngit clone -b issue53 https://github.com/pycompression/python-zlib-ng\r\n# Build Cpython\r\n./python -m ensurepip\r\n./python -m pip install pytest pytest-timeout \u003cpath to python-zlib-ng repo\u003e\r\n./python -m pytest \u003cpath to python-zlib-ng repo\u003e/tests/test_gzip_ng_threaded.py::test_threaded_program_can_exit_on_error\r\n```\r\n\r\nSince there are many code changes between 3.12 in 3.13 the underlying cause is surely there, but it is hard to pinpoint.\r\n\r\n\r\n\r\n### CPython versions tested on:\r\n\r\n3.13, CPython main branch\r\n\r\n### Operating systems tested on:\r\n\r\nLinux\n\n\u003c!-- gh-linked-prs --\u003e\n### Linked PRs\n* gh-124150\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/rhpvorderman","@type":"Person","name":"rhpvorderman"},"datePublished":"2024-09-11T09:58:04.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":13},"url":"https://github.com/123940/cpython/issues/123940"}