gh-150942: Speed up FrameLocalsProxy.values()

Lib/test/test_frame.py

@@ -557,6 +557,47 @@ def test_as_dict(self):
         with self.assertRaises(KeyError):
             d['non_exist']
 
+    def test_values_reference_ownership(self):
+        class Value:
+            pass
+
+        for duplicate_names in (False, True):
+            with self.subTest(duplicate_names=duplicate_names):
+                def make_frame(first, second):
+                    return sys._getframe()
+
+                if duplicate_names:
+                    make_frame.__code__ = make_frame.__code__.replace(
+                        co_varnames=('value', 'value'))
+
+                first = Value()
+                second = Value()
+                extra = Value()
+                refs = [weakref.ref(value) for value in (first, second, extra)]
+                frame = make_frame(first, second)
+                proxy = frame.f_locals
+                proxy['extra'] = extra
+                values = proxy.values()
+                if duplicate_names:
+                    self.assertEqual(values, [first, extra])
+                else:
+                    self.assertEqual(values, [first, second, extra])
+
+                frame.clear()
+                del first, second, extra
+                support.gc_collect()
+                self.assertIsNotNone(refs[0]())
+                self.assertIsNotNone(refs[2]())
+                if duplicate_names:
+                    self.assertIsNone(refs[1]())
+                else:
+                    self.assertIsNotNone(refs[1]())
+
+                values.clear()
+                support.gc_collect()
+                for ref in refs:
+                    self.assertIsNone(ref())
+
     def test_as_number(self):
         x = 1
         y = 2

Misc/NEWS.d/next/Core_and_Builtins/2026-10-03-10-40-00.gh-issue-150942.mK9qLs.rst

@@ -0,0 +1,2 @@
+Avoid redundant reference count updates in the ``values()`` method of the
+:attr:`frame.f_locals` proxy for optimized scopes.

Objects/frameobject.c

@@ -634,14 +634,15 @@ framelocalsproxy_values(PyObject *self, PyObject *Py_UNUSED(ignored))
             PyObject *name = PyTuple_GET_ITEM(co->co_localsplusnames, i);
             int first = framelocalsproxy_is_first_occurrence(seen, name);
             if (first == 1) {
-                if (PyList_Append(values, value) < 0) {
-                    Py_DECREF(value);
+                if (_PyList_AppendTakeRef((PyListObject *)values, value) < 0) {
                     goto error;
                 }
             }
-            Py_DECREF(value);
-            if (first < 0) {
-                goto error;
+            else {
+                Py_DECREF(value);
+                if (first < 0) {
+                    goto error;
+                }
             }
         }
     }