diff --git a/Misc/NEWS.d/next/Library/2026-05-18-15-30-34.gh-issue-146452.RM0EVJ.rst b/Misc/NEWS.d/next/Library/2026-05-18-15-30-34.gh-issue-146452.RM0EVJ.rst deleted file mode 100644 index 66f9acf6c710a79..000000000000000 --- a/Misc/NEWS.d/next/Library/2026-05-18-15-30-34.gh-issue-146452.RM0EVJ.rst +++ /dev/null @@ -1,2 +0,0 @@ -Fix race condition when pickling dictionaries in free threaded builds. Also -reduce critical section cover. diff --git a/Modules/_pickle.c b/Modules/_pickle.c index 201ea9af8b2a8bb..75e1c4dea85e004 100644 --- a/Modules/_pickle.c +++ b/Modules/_pickle.c @@ -3351,12 +3351,9 @@ batch_dict(PickleState *state, PicklerObject *self, PyObject *iter, PyObject *or * Returns 0 on success, -1 on error. * * Note that this currently doesn't work for protocol 0. - - * gh-146452: Wrap the dict iteration in a critical sections to prevent - * concurrent mutation from invalidating PyDict_Next() iteration state. */ static int -batch_dict_exact(PickleState *state, PicklerObject *self, PyObject *obj) +batch_dict_exact_impl(PickleState *state, PicklerObject *self, PyObject *obj) { PyObject *key = NULL, *value = NULL; int i; @@ -3373,19 +3370,9 @@ batch_dict_exact(PickleState *state, PicklerObject *self, PyObject *obj) /* Special-case len(d) == 1 to save space. */ if (dict_size == 1) { - int next; - Py_BEGIN_CRITICAL_SECTION(obj); - next = PyDict_Next(obj, &ppos, &key, &value); - if (next) { - Py_INCREF(key); - Py_INCREF(value); - } - Py_END_CRITICAL_SECTION(); - if (!next) { - PyErr_SetString(PyExc_RuntimeError, - "dictionary changed size during iteration"); - goto error; - } + PyDict_Next(obj, &ppos, &key, &value); + Py_INCREF(key); + Py_INCREF(value); if (save(state, self, key, 0) < 0) { goto error; } @@ -3405,18 +3392,9 @@ batch_dict_exact(PickleState *state, PicklerObject *self, PyObject *obj) i = 0; if (_Pickler_Write(self, &mark_op, 1) < 0) return -1; - int next; - while (1) { - Py_BEGIN_CRITICAL_SECTION(obj); - next = PyDict_Next(obj, &ppos, &key, &value); - if (next) { - Py_INCREF(key); - Py_INCREF(value); - } - Py_END_CRITICAL_SECTION(); - if (!next) { - break; - } + while (PyDict_Next(obj, &ppos, &key, &value)) { + Py_INCREF(key); + Py_INCREF(value); if (save(state, self, key, 0) < 0) { goto error; } @@ -3446,6 +3424,18 @@ batch_dict_exact(PickleState *state, PicklerObject *self, PyObject *obj) return -1; } +/* gh-146452: Wrap the dict iteration in a critical section to prevent + concurrent mutation from invalidating PyDict_Next() iteration state. */ +static int +batch_dict_exact(PickleState *state, PicklerObject *self, PyObject *obj) +{ + int ret; + Py_BEGIN_CRITICAL_SECTION(obj); + ret = batch_dict_exact_impl(state, self, obj); + Py_END_CRITICAL_SECTION(); + return ret; +} + static int save_dict(PickleState *state, PicklerObject *self, PyObject *obj) {