diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2026-07-14-20-19-48.gh-issue-152075.V9Rwhp.rst b/Misc/NEWS.d/next/Core_and_Builtins/2026-07-14-20-19-48.gh-issue-152075.V9Rwhp.rst new file mode 100644 index 00000000000000..84c7d36b97acba --- /dev/null +++ b/Misc/NEWS.d/next/Core_and_Builtins/2026-07-14-20-19-48.gh-issue-152075.V9Rwhp.rst @@ -0,0 +1,2 @@ +Reduced lock contention during LOAD_GLOBAL bytecode specialization under +free threading. diff --git a/Python/specialize.c b/Python/specialize.c index 773b55c329c772..05cb76ff015ff4 100644 --- a/Python/specialize.c +++ b/Python/specialize.c @@ -1457,6 +1457,14 @@ _Py_Specialize_LoadGlobal( PyObject *globals, PyObject *builtins, _Py_CODEUNIT *instr, PyObject *name) { +#ifdef Py_GIL_DISABLED + if (PyMutex_IsLocked(&globals->ob_mutex) || PyMutex_IsLocked(&builtins->ob_mutex)) { + // Skip specialization if either dictionary is locked to avoid lock + // contention. + unspecialize(instr); + return; + } +#endif Py_BEGIN_CRITICAL_SECTION2(globals, builtins); specialize_load_global_lock_held(globals, builtins, instr, name); Py_END_CRITICAL_SECTION2();