René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"ZoneInfo comparison fails on free-threaded build","articleBody":"# Bug report\n\n### Bug description:\n\n(originally noticed by @davidhewitt in https://github.com/python/cpython/issues/116738#issuecomment-2404360445)\n\nVery infrequently, PyO3 tests for timezone conversions will fail with errors like:\n\n```\n---- conversions::chrono_tz::tests::test_into_pyobject stdout ----\nthread 'conversions::chrono_tz::tests::test_into_pyobject' panicked at src/conversions/chrono_tz.rs:120:17:\nzoneinfo.ZoneInfo(key='UTC') != zoneinfo.ZoneInfo(key='UTC')\n```\n\nUnfortunately, I don't have an easier way to trigger this besides \"run the PyO3 tests over and over until you see a failure\", since I think triggering it requires many threads simultaneously using the C API which happens automatically with cargo for the PyO3 tests.\n\nThe test code is here:\n\nhttps://github.com/PyO3/pyo3/blob/eacebb8db101d05ae4ccf0396e314b098455ecd3/src/conversions/chrono_tz.rs#L116-L134\n\nI believe that rust is more or less doing the equivalent of this C code:\n\n```\n#include \u003cPython.h\u003e\n\nint main()\n{\n  if (Py_IsInitialized() == 0) {\n    Py_InitializeEx(0);\n\n    PyObject *mod = PyImport_ImportModule(\"zoneinfo\");\n\n    if (mod == NULL) {\n      PyErr_PrintEx(0);\n      return -1;\n    }\n\n    PyObject *zoneinfo = PyObject_GetAttrString(mod, \"ZoneInfo\");\n\n    if (zoneinfo == NULL) {\n      PyErr_PrintEx(0);\n      return -1;\n    }\n\n    PyObject *arg = PyUnicode_FromString(\"Europe/Paris\");\n\n    PyObject *obj1 = PyObject_CallOneArg(zoneinfo, arg);\n    PyObject *obj2 = PyObject_CallOneArg(zoneinfo, arg);\n\n    PyObject *result = PyObject_RichCompare(obj1, obj2, Py_EQ);\n\n    PyObject_Print(result, stderr, Py_PRINT_RAW);\n  }\n\n  return 0;\n}\n```\n\nThis doesn't fail, which makes me suspect triggering it requires touching the C API in other threads.\n\n### CPython versions tested on:\n\n3.13\n\n### Operating systems tested on:\n\nmacOS\n\n\u003c!-- gh-linked-prs --\u003e\n### Linked PRs\n* gh-125281\n* gh-125414\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/ngoldbaum","@type":"Person","name":"ngoldbaum"},"datePublished":"2024-10-10T09:44:51.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":10},"url":"https://github.com/125243/cpython/issues/125243"}