gh-131586: Avoid refcount contention in some "special" calls (#131588)

In the free threaded build, the `_PyObject_LookupSpecial()` call can lead to
reference count contention on the returned function object becuase it
doesn't use stackrefs. Refactor some of the callers to use
`_PyObject_MaybeCallSpecialNoArgs`, which uses stackrefs internally.

This fixes the scaling bottleneck in the "lookup_special" microbenchmark
in `ftscalingbench.py`. However, the are still some uses of
`_PyObject_LookupSpecial()` that need to be addressed in future PRs.
This commit is contained in:
Sam Gross 2025-03-26 14:38:47 -04:00 committed by GitHub
parent 3d4ac1a2c2
commit 67fbfb42bd
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16 changed files with 450 additions and 374 deletions

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@ -433,6 +433,12 @@ static void
gc_visit_thread_stacks(PyInterpreterState *interp, struct collection_state *state)
{
_Py_FOR_EACH_TSTATE_BEGIN(interp, p) {
_PyCStackRef *c_ref = ((_PyThreadStateImpl *)p)->c_stack_refs;
while (c_ref != NULL) {
gc_visit_stackref(c_ref->ref);
c_ref = c_ref->next;
}
for (_PyInterpreterFrame *f = p->current_frame; f != NULL; f = f->previous) {
if (f->owner >= FRAME_OWNED_BY_INTERPRETER) {
continue;