From a4b77495da7b42118c24db0239852ef5118f4fe3 Mon Sep 17 00:00:00 2001 From: Sam Gross Date: Thu, 21 Nov 2024 16:18:59 +0000 Subject: [PATCH] gh-127065: Make `methodcaller` thread-safe in free threading build The `methodcaller` C vectorcall implementation uses an arguments array that is shared across calls. The first argument is modified on every invocation. This isn't thread-safe in the free threading build. I think it's also not safe in general, but for now just disable it in the free threading build. --- .../2024-11-21-16-23-16.gh-issue-127065.cfL1zd.rst | 2 ++ Modules/_operator.c | 9 +++++++++ 2 files changed, 11 insertions(+) create mode 100644 Misc/NEWS.d/next/Library/2024-11-21-16-23-16.gh-issue-127065.cfL1zd.rst diff --git a/Misc/NEWS.d/next/Library/2024-11-21-16-23-16.gh-issue-127065.cfL1zd.rst b/Misc/NEWS.d/next/Library/2024-11-21-16-23-16.gh-issue-127065.cfL1zd.rst new file mode 100644 index 00000000000000..83457da467ffa9 --- /dev/null +++ b/Misc/NEWS.d/next/Library/2024-11-21-16-23-16.gh-issue-127065.cfL1zd.rst @@ -0,0 +1,2 @@ +Fix crash when calling a :func:`operator.methodcaller` instance from +multiple threads in the free threading build. diff --git a/Modules/_operator.c b/Modules/_operator.c index 7e0d1f3df87e4d..6c1945174ab7cd 100644 --- a/Modules/_operator.c +++ b/Modules/_operator.c @@ -1602,6 +1602,7 @@ typedef struct { vectorcallfunc vectorcall; } methodcallerobject; +#ifndef Py_GIL_DISABLED static int _methodcaller_initialize_vectorcall(methodcallerobject* mc) { PyObject* args = mc->xargs; @@ -1664,6 +1665,7 @@ methodcaller_vectorcall( (PyTuple_GET_SIZE(mc->xargs)) | PY_VECTORCALL_ARGUMENTS_OFFSET, mc->vectorcall_kwnames); } +#endif /* AC 3.5: variable number of arguments, not currently support by AC */ @@ -1703,7 +1705,14 @@ methodcaller_new(PyTypeObject *type, PyObject *args, PyObject *kwds) mc->vectorcall_args = 0; +#ifdef Py_GIL_DISABLED + // gh-127065: The current implementation of methodcaller_vectorcall + // is not thread-safe because it modifies the `vectorcall_args` array, + // which is shared across calls. + mc->vectorcall = NULL; +#else mc->vectorcall = (vectorcallfunc)methodcaller_vectorcall; +#endif PyObject_GC_Track(mc); return (PyObject *)mc;