gh-123923: Defer refcounting for `f_executable` in `_PyInterpreterFrame` (#123924)

Use a `_PyStackRef` and defer the reference to `f_executable` when
possible. This avoids some reference count contention in the common case
of executing the same code object from multiple threads concurrently in
the free-threaded build.

1 files changed, 7 insertions, 0 deletions

diff --git a/Python/gc.c b/Python/gc.c
index 3d36792..024d041 100644
--- a/Python/gc.c
+++ b/Python/gc.c
@@ -535,6 +535,13 @@ visit_decref(PyObject *op, void *parent)
 }
 
 int
+_PyGC_VisitStackRef(_PyStackRef *ref, visitproc visit, void *arg)
+{
+    Py_VISIT(PyStackRef_AsPyObjectBorrow(*ref));
+    return 0;
+}
+
+int
 _PyGC_VisitFrameStack(_PyInterpreterFrame *frame, visitproc visit, void *arg)
 {
     _PyStackRef *ref = _PyFrame_GetLocalsArray(frame);