Free threaded scaling issues with `@classmethod` and `@staticmethod`

[colesbury]

Bug report

We have reference count contention from:

1. The classmethod object, which is stored in the MRO cache. This should be pretty easy to fix (enable deferred reference counting when creating the object).

2. sm_descr_get increfs sm->sm_callable

3. cm_descr_get creates a new PyMethod_New, which increfs cm->cm_callable and the containing class

ftscalingbench.py

class MyClassMethod:
    @classmethod
    def my_classmethod(cls):
        return cls

    @staticmethod
    def my_staticmethod():
        pass

@register_benchmark
def classmethod_call():
    obj = MyClassMethod()
    for _ in range(1000 * WORK_SCALE):
        obj.my_classmethod()

@register_benchmark
def staticmethod_call():
    obj = MyClassMethod()
    for _ in range(1000 * WORK_SCALE):
        obj.my_staticmethod()

Linked PRs

• gh-145779: Improve classmethod/staticmethod scaling in free-threaded build #145826
• [3.14] gh-145779: Improve classmethod/staticmethod scaling in free-threaded build (gh-145826) #146088

[brijkapadia]

The classmethod and staticmethod objects, which are stored in the MRO cache. This should be pretty easy to fix (enable deferred reference counting when creating the object).

Don't staticmethod objects already use deferred reference counting?

[colesbury]

Yes

[colesbury]

I've edited the issue description