gh-112087: Use QSBR technique for list_new/clear for free-thread build

Objects/listobject.c

@@ -502,7 +502,16 @@ list_item(PyObject *aa, Py_ssize_t i)
  PyErr_SetObject(PyExc_IndexError, &_Py_STR(list_err));
  return NULL;
  }
- return Py_NewRef(a->ob_item[i]);
+ PyObject *item;
+ Py_BEGIN_CRITICAL_SECTION(a);
+#ifdef Py_GIL_DISABLED
+ if (!_Py_IsOwnedByCurrentThread((PyObject *)a) && !_PyObject_GC_IS_SHARED(a)){
+ _PyObject_GC_SET_SHARED(a);
+ }
+#endif
+ item = Py_NewRef(a->ob_item[i]);
+ Py_END_CRITICAL_SECTION();
+ return item;
 }
 
 static PyObject *
@@ -658,7 +667,7 @@ list_repeat(PyObject *aa, Py_ssize_t n)
 }
 
 static void
-list_clear(PyListObject *a)
+list_clear_impl(PyListObject *a, bool is_resize)
 {
  PyObject **items = a->ob_item;
  if (items == NULL){
@@ -674,17 +683,31 @@ list_clear(PyListObject *a)
  while (--i >= 0){
  Py_XDECREF(items[i]);
  }
- // TODO: Use QSBR technique, if the list is shared between threads,
- PyMem_Free(items);
-
+#ifdef Py_GIL_DISABLED
+ bool use_qsbr = is_resize && _PyObject_GC_IS_SHARED(a);
+#else
+ bool use_qsbr = false;
+#endif
+ if (use_qsbr){
+ _PyMem_FreeDelayed(items);
+ }
+ else{
+ PyMem_Free(items);
+ }
  // Note that there is no guarantee that the list is actually empty
  // at this point, because XDECREF may have populated it indirectly again!
 }
 
+static void
+list_clear(PyListObject *a)
+{
+ list_clear_impl(a, true);
+}
+
 static int
 list_clear_slot(PyObject *self)
 {
-list_clear((PyListObject *)self);
+list_clear_impl((PyListObject *)self, false);
  return 0;
 }