gh-112087: Test fix for test_sched leak

Author: corona10

Include/internal/pycore_gc.h

@@ -288,6 +288,9 @@ extern PyObject *_PyGC_GetReferrers(PyInterpreterState *interp, PyObject *objs);
 extern void _PyGC_ClearAllFreeLists(PyInterpreterState *interp);
 extern void _Py_ScheduleGC(PyThreadState *tstate);
 extern void _Py_RunGC(PyThreadState *tstate);
+#ifdef Py_GIL_DISABLED
+extern void _PyGC_Clear_DelayedObjects(PyInterpreterState *interp);
+#endif
 
 #ifdef __cplusplus
 }

Python/gc_free_threading.c

@@ -1154,6 +1154,7 @@ gc_collect_main(PyThreadState *tstate, int generation, _PyGC_Reason reason)
         }
     }
 
+    _PyGC_Clear_DelayedObjects(interp);
     /* Update stats */
     struct gc_generation_stats *stats = &gcstate->generation_stats[generation];
     stats->collections++;
@@ -1758,4 +1759,16 @@ _PyGC_ClearAllFreeLists(PyInterpreterState *interp)
     HEAD_UNLOCK(&_PyRuntime);
 }
 
+void
+_PyGC_Clear_DelayedObjects(PyInterpreterState *interp)
+{
+    HEAD_LOCK(&_PyRuntime);
+    PyThreadState *tstate = interp->threads.head;
+    while (tstate != NULL) {
+        _PyMem_ProcessDelayed(tstate);
+        tstate = (PyThreadState *)tstate->next;
+    }
+    HEAD_UNLOCK(&_PyRuntime);
+}
+
 #endif  // Py_GIL_DISABLED