pythongh-118527: Use deferred reference counting for C functions on modules (python#118529)

colesbury · web-flow · commit 608192ee2f6c · 2024-05-03T11:33:05.000-04:00
This addresses a scaling bottleneck in the free-threaded build when
calling functions like `math.floor()` concurrently from multiple
threads.
diff --git a/Objects/moduleobject.c b/Objects/moduleobject.c
@@ -183,6 +183,7 @@ _add_methods_to_object(PyObject *module, PyObject *name, PyMethodDef *functions)
         if (func == NULL) {
             return -1;
         }
+        _PyObject_SetDeferredRefcount(func);
         if (PyObject_SetAttrString(module, fdef->ml_name, func) != 0) {
             Py_DECREF(func);
             return -1;

Original file line number	Diff line number	Diff line change
`@@ -183,6 +183,7 @@ _add_methods_to_object(PyObject module, PyObject name, PyMethodDef *functions)`
`183`	`183`	`if (func == NULL) {`
`184`	`184`	`return -1;`
`185`	`185`	`}`
	`186`	`+ _PyObject_SetDeferredRefcount(func);`
`186`	`187`	`if (PyObject_SetAttrString(module, fdef->ml_name, func) != 0) {`
`187`	`188`	`Py_DECREF(func);`
`188`	`189`	`return -1;`