René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"sys.settrace dramatic slowdown in 3.12","articleBody":"# Bug report\r\n\r\n## Checklist\r\n\r\n- [x] I am confident this is a bug in CPython, not a bug in a third-party project\r\n- [x] I have searched the CPython issue tracker, and am confident this bug has not been reported before\r\n\r\n## A clear and concise description of the bug\r\n\r\nA bug report in coverage (https://github.com/nedbat/coveragepy/issues/1665) is reduced here to a pure do-nothing trace function for sys.settrace.\r\n\r\nReproduction:\r\n\r\n```\r\n% git clone https://github.com/nedbat/ndindex\r\n\r\n% cd ndindex\r\n\r\n% python3.11 -VV\r\nPython 3.11.4 (main, Jun  7 2023, 08:42:37) [Clang 14.0.3 (clang-1403.0.22.14.1)]\r\n\r\n% python3.11 -m venv v311\r\n\r\n% ./v311/bin/pip install numpy\r\n\r\n% python3.12 -VV\r\nPython 3.12.0b4 (main, Jul 11 2023, 20:38:26) [Clang 14.0.3 (clang-1403.0.22.14.1)]\r\n\r\n% python3.12 -m venv v312\r\n\r\n% ./v312/bin/pip install --pre --extra-index https://pypi.anaconda.org/scientific-python-nightly-wheels/simple numpy\r\n\r\n% # Run the code without the trace function.\r\n% for x in 1 2 3; time ./v311/bin/python -m ndindex.tests.justdoit notrace\r\n./v311/bin/python -m ndindex.tests.justdoit notrace  7.05s user 0.37s system 108% cpu 6.813 total\r\n./v311/bin/python -m ndindex.tests.justdoit notrace  7.04s user 0.34s system 109% cpu 6.724 total\r\n./v311/bin/python -m ndindex.tests.justdoit notrace  7.00s user 0.35s system 109% cpu 6.696 total\r\n\r\n% # 3.12 is slightly faster without the trace function.\r\n% for x in 1 2 3; time ./v312/bin/python -m ndindex.tests.justdoit notrace\r\n./v312/bin/python -m ndindex.tests.justdoit notrace  6.56s user 0.30s system 106% cpu 6.422 total\r\n./v312/bin/python -m ndindex.tests.justdoit notrace  6.48s user 0.31s system 106% cpu 6.359 total\r\n./v312/bin/python -m ndindex.tests.justdoit notrace  6.38s user 0.28s system 107% cpu 6.217 total\r\n\r\n% # 3.11 with tracing is about 3x slower.\r\n% for x in 1 2 3; time ./v311/bin/python -m ndindex.tests.justdoit trace\r\n./v311/bin/python -m ndindex.tests.justdoit trace  22.64s user 0.51s system 101% cpu 22.772 total\r\n./v311/bin/python -m ndindex.tests.justdoit trace  21.92s user 0.46s system 101% cpu 21.979 total\r\n./v311/bin/python -m ndindex.tests.justdoit trace  21.55s user 0.35s system 102% cpu 21.379 total\r\n\r\n% # 3.12 with tracing is 7x slower.\r\n% for x in 1 2 3; time ./v312/bin/python -m ndindex.tests.justdoit trace\r\n./v312/bin/python -m ndindex.tests.justdoit trace  49.47s user 0.40s system 100% cpu 49.676 total\r\n./v312/bin/python -m ndindex.tests.justdoit trace  49.53s user 0.39s system 100% cpu 49.784 total\r\n./v312/bin/python -m ndindex.tests.justdoit trace  50.44s user 0.38s system 100% cpu 50.739 total\r\n```\r\n\r\nI don't know if the unusual numpy build has something to do with this.  \r\n\n\n\u003c!-- gh-linked-prs --\u003e\n### Linked PRs\n* gh-107780\n* gh-107841\n* gh-114986\n* gh-117133\n* gh-117393\n* gh-118127\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/nedbat","@type":"Person","name":"nedbat"},"datePublished":"2023-08-05T22:12:36.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":37},"url":"https://github.com/107674/cpython/issues/107674"}