Remove deprecated `async.iscoroutinefunction` for 3.16

[sobolevn]

Feature or enhancement

Refs #122858
Refs #122875

It is scheduled to be removed in 3.16:

cpython/Lib/asyncio/coroutines.py

Lines 16 to 32 in 46a2c11

	# A marker for iscoroutinefunction.
	_is_coroutine = object()
	def iscoroutinefunction(func):
	import warnings
	"""Return True if func is a decorated coroutine function."""
	warnings._deprecated("asyncio.iscoroutinefunction",
	f"{warnings._DEPRECATED_MSG}; "
	"use inspect.iscoroutinefunction() instead",
	remove=(3,16))
	return _iscoroutinefunction(func)
	def _iscoroutinefunction(func):
	return (inspect.iscoroutinefunction(func) or
	getattr(func, '_is_coroutine', None) is _is_coroutine)

Linked PRs

• gh-149600: Remove deprecated asyncio.iscoroutinefunction function #149601

[cdce8p]

Would it be too much hassle to hold off on the removal a bit longer? While switching to inspect isn't difficult, there are unfortunately packages which are no longer maintained and thus would be broken. In particular backoff with over 144 mil. downloads last month. I just checked the dependency tree for Home Assistant and it's still used by at least 22 of our dependencies.

The repo was archived last year.
https://github.com/litl/backoff/
litl/backoff#220

[sobolevn]

@cdce8p backoff is archieved.

I don't think that it will ever change its API.
So, what can be different next year / release?

[cdce8p]

@cdce8p backoff is archieved.

Yeah, I mentioned as much in my message.

So, what can be different next year / release?

Not much. I guess it's just a question if the removal is worth it. A few on-off projects are one thing but backoff is still used by a lot of packages which would all need to adapt. That's a huge cascading change which has the potential to significantly impact the adoption of 3.16 across the ecosystem.

[sobolevn]

I guess it's just a question if the removal is worth it.

In my opinion - yes, it is :)
Older API had multiple real technical problems that were solved with inspect.markcoroutinefunction and inspect.iscoroutinefunction. We issued a warning for this a long time ago, no issues from users were created because of that: https://github.com/python/cpython/issues?q=is%3Aissue%20state%3Aopen%20iscoroutinefunction Plus, there's a clear migration path.

If you want to discuss the deprecation cancelation / prolongation, there must be real solid technical reasons that outweight all the pro's.

[cdce8p]

Plus, there's a clear migration path.

I agree and that's always greatly appreciated!

If you want to discuss the deprecation cancelation / prolongation, there must be real solid technical reasons that outweight all the pro's.

Must admit that I only skimmed #149601 but isn't asyncio.iscoroutinefunction basically an alias for inspect.iscoroutinefunction at this point? That's why I thought to comment here at all. I fully agree that cleanup, especially of problematic APIs, is worth it. That calculation is a bit different for aliases though at least IMO. E.g. while someday I'd love to get rid of typing.Union from a cleanup perspective, I don't expect that will ever happen. The ecosystem cost might simply be too high for it to be worth it.

Anyway, I checked the fork network on Github and it looks like a replacement fork might be python-backoff. It's already at 5M monthly downloads.
https://github.com/python-backoff/backoff