bpo-1635741: Explict GC collect after PyInterpreterState_Clear() (GH-21902)

Fix a reference cycle by triggering an explicit GC collection
after calling PyInterpreterState_Clear().

diff --git a/Python/pylifecycle.c b/Python/pylifecycle.c
index 2d219a4a3a8b0db5a9c4fd8497565491aa413dd2..ab5a6767864dc596bdb94a8163c88888fa391062 100644 (file)
--- a/Python/pylifecycle.c
+++ b/Python/pylifecycle.c
@@ -1286,10 +1286,8 @@ finalize_interp_clear(PyThreadState *tstate)
     /* Clear interpreter state and all thread states */
     PyInterpreterState_Clear(tstate->interp);
 
-    /* Trigger a GC collection on subinterpreters*/
-    if (!is_main_interp) {
-        _PyGC_CollectNoFail();
-    }
+    /* Last explicit GC collection */
+    _PyGC_CollectNoFail();
 
     /* Clear all loghooks */
     /* Both _PySys_Audit function and users still need PyObject, such as tuple.