fix: add critical section for grouper_next

KowalskiThomas · KowalskiThomas · commit ba8c0cd0f064 · 2026-06-02T16:27:59.000+02:00
diff --git a/Modules/itertoolsmodule.c b/Modules/itertoolsmodule.c
@@ -529,7 +529,7 @@ groupby_step(groupbyobject *gbo)
 }
 
 static PyObject *
-groupby_next(PyObject *op)
+groupby_next_lock_held(PyObject *op)
 {
     PyObject *grouper;
     groupbyobject *gbo = groupbyobject_CAST(op);
@@ -574,6 +574,16 @@ groupby_next(PyObject *op)
     return _PyTuple_FromPairSteal(Py_NewRef(gbo->currkey), grouper);
 }
 
+static PyObject *
+groupby_next(PyObject *op)
+{
+    PyObject *result;
+    Py_BEGIN_CRITICAL_SECTION(op);
+    result = groupby_next_lock_held(op);
+    Py_END_CRITICAL_SECTION()
+    return result;
+}
+
 static PyType_Slot groupby_slots[] = {
     {Py_tp_dealloc, groupby_dealloc},
     {Py_tp_getattro, PyObject_GenericGetAttr},
@@ -659,7 +669,7 @@ _grouper_traverse(PyObject *op, visitproc visit, void *arg)
 }
 
 static PyObject *
-_grouper_next(PyObject *op)
+_grouper_next_lock_held(PyObject *op)
 {
     _grouperobject *igo = _grouperobject_CAST(op);
     groupbyobject *gbo = groupbyobject_CAST(igo->parent);
@@ -695,6 +705,16 @@ _grouper_next(PyObject *op)
     return r;
 }
 
+static PyObject *
+_grouper_next(PyObject *op)
+{
+    PyObject *result;
+    Py_BEGIN_CRITICAL_SECTION(_grouperobject_CAST(op)->parent);
+    result = _grouper_next_lock_held(op);
+    Py_END_CRITICAL_SECTION()
+    return result;
+}
+
 static PyType_Slot _grouper_slots[] = {
     {Py_tp_dealloc, _grouper_dealloc},
     {Py_tp_getattro, PyObject_GenericGetAttr},
