gh-158880: Fix asyncio ps showing tasks from only one interpreter

[deadlovelll]

Fix asyncio ps showing tasks from only one interpreter

For details see gh-158880

[maurycy]

asyncio.sleep feels like a flaky risk. What do you think about using busy_retry instead?

[deadlovelll]

Thanks! I fixed it

[maurycy]

Unless I'm missing something, get_async_stack_trace() still has the same problem. Maybe it should be a follow-up, though.

[deadlovelll]

Yeah, it has the problem, i planned to open a separate issue for this to avoid "big-bang" pr

[maurycy]

This is just a list:

cpython/Modules/_remote_debugging/module.c

Lines 719 to 720 in 9028df3

	uintptr_t current_interpreter = self->interpreter_addr;
	while (current_interpreter != 0) {

cpython/Modules/_remote_debugging/module.c

Lines 884 to 885 in 9028df3

	current_interpreter = GET_MEMBER(uintptr_t, interp_state_buffer,
	self->debug_offsets.interpreter_state.next);

cpython/Modules/_remote_debugging/frames.c

Lines 459 to 462 in 182f323

	const size_t MAX_INTERPRETERS = 256;
	size_t interp_count = 0;
	while (current_interp != 0 && interp_count < MAX_INTERPRETERS) {

Is there a reproducible race scenario where we'd see a cycle? (It was quiet easy to reproduce issues like ABA.)

[deadlovelll]

No, I couldn't reproduce a cycle. I thought the interpreter walk could loop
because of the previous PR, that's why I added the set. I agree with your suggestion and will rework it soon

[maurycy]

One way to silence https://github.com/python/cpython/actions/runs/37499870518/job/112393935495#step:6:1023 is by wrapping this in except TRANSIENT_ERRORS:

Perhaps a better approach, similar to #158801

cpython/Lib/test/test_external_inspection.py

Lines 2440 to 2460 in 0e75a05

	from _queue import SimpleQueue
	from test import support
	go = threading.Lock()
	stop = threading.Lock()
	go.acquire()
	stop.acquire()
	ready = SimpleQueue()
	def leaf():
	ready.put(None)
	stop.acquire()
	def start_leaf():
	ready.put(None)
	go.acquire()
	leaf()
	def park():
	ready.put(None)
	stop.acquire()

cpython/Lib/test/test_external_inspection.py

Lines 2469 to 2482 in 0e75a05

	# SimpleQueue.put() and Lock.acquire() do not push Python frames.
	# Once notified, the worker's stack stays stable until go is released.
	threading.Thread(target=leaf, daemon=True).start()
	ready.get(timeout=support.SHORT_TIMEOUT)
	for _ in range(16):
	threading.Thread(target=park, daemon=True).start()
	ready.get(timeout=support.SHORT_TIMEOUT)
	threading.Thread(target=start_leaf, daemon=True).start()
	ready.get(timeout=support.SHORT_TIMEOUT)
	u = RemoteUnwinder(os.getpid(), all_threads=True, cache_frames=False)
	assert leaf_count(u) == 1
	go.release()
	ready.get(timeout=support.SHORT_TIMEOUT)