gh-104028: Reduce objects creation while calling callback function on gc

Author: corona10

Misc/NEWS.d/next/Core and Builtins/2023-05-01-14-10-38.gh-issue-104028.dxfh13.rst

@@ -0,0 +1,2 @@
+Reduce objects creation while calling callback function on gc. Patch by
+Dong-hee Na.

Modules/gcmodule.c

@@ -1388,10 +1388,13 @@ invoke_gc_callback(PyThreadState *tstate, const char *phase,
             return;
         }
     }
+
+    PyObject *phase_obj = PyUnicode_FromString(phase);
+    PyObject *stack[] = {phase_obj, info};
     for (Py_ssize_t i=0; i<PyList_GET_SIZE(gcstate->callbacks); i++) {
         PyObject *r, *cb = PyList_GET_ITEM(gcstate->callbacks, i);
         Py_INCREF(cb); /* make sure cb doesn't go away */
-        r = PyObject_CallFunction(cb, "sO", phase, info);
+        r = PyObject_Vectorcall(cb, stack, 2, NULL);
         if (r == NULL) {
             PyErr_WriteUnraisable(cb);
         }
@@ -1400,6 +1403,7 @@ invoke_gc_callback(PyThreadState *tstate, const char *phase,
         }
         Py_DECREF(cb);
     }
+    Py_DECREF(phase_obj);
     Py_XDECREF(info);
     assert(!_PyErr_Occurred(tstate));
 }