deprecate the asyncio child watchers system #94597

New issue

Closed

deprecate the asyncio child watchers system#94597

Assignees

Labels

3.12only security fixesstdlibPython modules in the Lib dirtopic-asyncio

Description

graingert

opened

on Jul 6, 2022

Deprecate the child watchers system and the policy system in favour of
asyncio.Runner(loop_factory=asyncio.ProactorEventLoop/asyncio.SelectorEventLoop/uvloop.new_event_loop)
that would be deprecating:

asyncio.get_event_loop() # already deprecated unless the loop is running asyncio.set_event_loop()  # asyncio.set_event_loop(None) should probably be exemptasyncio.get_event_loop_policy()asyncio.set_event_loop_policy()  # asyncio.set_event_loop_policy(None) should probably be exemptasyncio.set_child_watcher()asyncio.get_child_watcher()  # `_make_subprocess_transport` will instead attempt to use os.open_pidfd and fallback to starting a thread

I'd also like to introduce a new API:asyncio.EventLoop implemented as:

if sys.platform == "win32":    EventLoop = ProactorEventLoopelse:    EventLoop = SelectorEventLoop

asyncio.new_event_loop() will issue a DeprecationWarning if the current policy is not the default policy, and then in 3 releases become an alias ofasyncio.EventLoop

Originally posted by@graingert in#93896 (comment)