From 5e2c992e3b255a1ec1b9ea45ebffad1201866e1e Mon Sep 17 00:00:00 2001 From: Sam Gross Date: Fri, 16 Jan 2026 11:55:40 -0500 Subject: [PATCH] [3.14] gh-143880: Fix data race in `functools.partial` in free threading build (GH-143882) gh-143880: Fix data race in `functools.partial` in free threading build The assignment to `pto->vectorcall` isn't thread-safe in the free threading build. Note that this is already fixed in the main branch. (cherry picked from commit 0042384bd56cf88c9bf868776247ef00b34719de) Co-authored-by: Sam Gross --- .../next/Library/2026-01-15-13-03-22.gh-issue-143880.sWoLsf.rst | 1 + Modules/_functoolsmodule.c | 2 ++ 2 files changed, 3 insertions(+) create mode 100644 Misc/NEWS.d/next/Library/2026-01-15-13-03-22.gh-issue-143880.sWoLsf.rst diff --git a/Misc/NEWS.d/next/Library/2026-01-15-13-03-22.gh-issue-143880.sWoLsf.rst b/Misc/NEWS.d/next/Library/2026-01-15-13-03-22.gh-issue-143880.sWoLsf.rst new file mode 100644 index 00000000000000..b77f86e5eb8f8f --- /dev/null +++ b/Misc/NEWS.d/next/Library/2026-01-15-13-03-22.gh-issue-143880.sWoLsf.rst @@ -0,0 +1 @@ +Fix data race in :func:`functools.partial` in the :term:`free threading` build. diff --git a/Modules/_functoolsmodule.c b/Modules/_functoolsmodule.c index cbbba322a1825c..40c573b3fdf7b6 100644 --- a/Modules/_functoolsmodule.c +++ b/Modules/_functoolsmodule.c @@ -220,7 +220,9 @@ partial_vectorcall_fallback(PyThreadState *tstate, partialobject *pto, PyObject *const *args, size_t nargsf, PyObject *kwnames) { +#ifndef Py_GIL_DISABLED pto->vectorcall = NULL; +#endif Py_ssize_t nargs = PyVectorcall_NARGS(nargsf); return _PyObject_MakeTpCall(tstate, (PyObject *)pto, args, nargs, kwnames);