gh-119710: Let asyncio Process.wait() finish on only process exit. by tapetersen · Pull Request #151983 · python/cpython · GitHub

gh-119710: Let asyncio Process.wait() finish on only process exit

Letting Process.wait() only wait on actual process return is closer to how it's documented and consistent with Popen.wait(). This also reduces complexity for waking waiters which was inconsistend depending on ordering of wait/exit.

All commit authors signed the Contributor License Agreement.

Letting Process.wait() only wait on actual process return is closer to how it's documented and consistent with Popen.wait(). This also reduces complexity for waking waiters which was inconsistend depending on ordering of wait/exit.

This allows waiters to be scheduled after protocol.process_exited and/or connection_lost callbacks.

I simplified the added test and also fixed it, now it correctly fails on main branch but passes on this. here's the failure on windows:

======================================================================
ERROR: test_wait_even_if_pipe_is_open (test.test_asyncio.test_subprocess.SubprocessProactorTests.test_wait_even_if_pipe_is_open)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "D:\cpython\Lib\asyncio\tasks.py", line 488, in wait_for
    return await fut
           ^^^^^^^^^
  File "D:\cpython\Lib\asyncio\subprocess.py", line 137, in wait
    return await self._transport._wait()
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "D:\cpython\Lib\asyncio\base_subprocess.py", line 255, in _wait
    return await waiter
           ^^^^^^^^^^^^
asyncio.exceptions.CancelledError

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "D:\cpython\Lib\test\test_asyncio\test_subprocess.py", line 446, in test_wait_even_if_pipe_is_open
    self.loop.run_until_complete(run())
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^
  File "D:\cpython\Lib\asyncio\base_events.py", line 725, in run_until_complete
    return future.result()
           ~~~~~~~~~~~~~^^
  File "D:\cpython\Lib\test\test_asyncio\test_subprocess.py", line 436, in run
    returncode = await asyncio.wait_for(
                 ^^^^^^^^^^^^^^^^^^^^^^^
        wait_proc, timeout=support.SHORT_TIMEOUT)
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "D:\cpython\Lib\asyncio\tasks.py", line 487, in wait_for
    async with timeouts.timeout(timeout):
               ~~~~~~~~~~~~~~~~^^^^^^^^^
  File "D:\cpython\Lib\asyncio\timeouts.py", line 115, in __aexit__
    raise TimeoutError from exc_val
TimeoutError

----------------------------------------------------------------------
Ran 41 tests in 35.871s

Thanks @tapetersen for the PR, and @kumaraditya303 for merging it 🌮🎉.. I'm working now to backport this PR to: 3.13, 3.14, 3.15.
🐍🍒⛏🤖

GH-154170 is a backport of this pull request to the 3.15 branch.

GH-154171 is a backport of this pull request to the 3.14 branch.

GH-154172 is a backport of this pull request to the 3.13 branch.

@kumaraditya303 Thanks for the review and windows fix.

… and not wait for closing of pipes (pythonGH-151983) (cherry picked from commit f252132) Co-authored-by: Tobias Alex-Petersen <tobias.alex.petersen@gmail.com> Co-authored-by: Kumar Aditya <kumaraditya@python.org>

…t and not wait for closing of pipes (GH-151983) (#154172) gh-119710: fix asyncio Process.wait() to finish on process exit and not wait for closing of pipes (GH-151983) (cherry picked from commit f252132) Co-authored-by: Tobias Alex-Petersen <tobias.alex.petersen@gmail.com> Co-authored-by: Kumar Aditya <kumaraditya@python.org>

…t and not wait for closing of pipes (GH-151983) (#154171) gh-119710: fix asyncio Process.wait() to finish on process exit and not wait for closing of pipes (GH-151983) (cherry picked from commit f252132) Co-authored-by: Tobias Alex-Petersen <tobias.alex.petersen@gmail.com> Co-authored-by: Kumar Aditya <kumaraditya@python.org>

…t and not wait for closing of pipes (GH-151983) (#154170) * gh-119710: fix asyncio Process.wait() to finish on process exit and not wait for closing of pipes (GH-151983) (cherry picked from commit f252132) Co-authored-by: Tobias Alex-Petersen <tobias.alex.petersen@gmail.com> Co-authored-by: Kumar Aditya <kumaraditya@python.org>

bedevere-app Bot mentioned this pull request Jun 23, 2026

asyncio proc.kill() and proc.wait() are counter intuitive #119710

Closed

tapetersen force-pushed the gh-119710-subprocess-wait-hang branch 3 times, most recently from e774576 to f6df3f5 Compare June 23, 2026 12:07

tapetersen commented Jun 23, 2026

View reviewed changes

Comment thread Lib/test/test_asyncio/test_subprocess.py

tapetersen commented Jun 23, 2026

View reviewed changes

Comment thread Lib/asyncio/base_subprocess.py Outdated

tapetersen marked this pull request as ready for review June 23, 2026 12:21

tapetersen requested review from 1st1, asvetlov, kumaraditya303 and willingc as code owners June 23, 2026 12:21

bedevere-app Bot added the awaiting review label Jun 23, 2026

kumaraditya303 reviewed Jul 17, 2026

View reviewed changes

Comment thread Lib/test/test_asyncio/test_subprocess.py Outdated

tapetersen force-pushed the gh-119710-subprocess-wait-hang branch from f6df3f5 to e703a76 Compare July 17, 2026 13:57

Use sleep(0) in test per review comments.

13f7cc7

kumaraditya303 reviewed Jul 17, 2026

View reviewed changes

Comment thread Lib/test/test_asyncio/test_subprocess.py Outdated

kumaraditya303 reviewed Jul 17, 2026

View reviewed changes

Comment thread Lib/test/test_asyncio/test_subprocess.py Outdated

kumaraditya303 added topic-asyncio needs backport to 3.15 bugs and security fixes labels Jul 17, 2026

kumaraditya303 reviewed Jul 17, 2026

View reviewed changes

Comment thread Lib/test/test_asyncio/test_subprocess.py Outdated

tapetersen and others added 4 commits July 19, 2026 11:46

Change to test_timeount to use support.SHORT_TIMEOUT

1110364

Remove internals heavy asyncio test that's covered elsewhere.

bc780d4

Move waiter wakeup to later in _process_exited

d8276f8

This allows waiters to be scheduled after protocol.process_exited and/or connection_lost callbacks.

fix test

d723a09

kumaraditya303 added needs backport to 3.13 only security fixes needs backport to 3.14 bugs and security fixes labels Jul 19, 2026

kumaraditya303 approved these changes Jul 19, 2026

View reviewed changes

bedevere-app Bot added awaiting merge and removed awaiting review labels Jul 19, 2026

kumaraditya303 merged commit f252132 into python:main Jul 19, 2026
59 checks passed

bedevere-app Bot removed the awaiting merge label Jul 19, 2026

bedevere-app Bot removed the needs backport to 3.15 bugs and security fixes label Jul 19, 2026

bedevere-app Bot removed the needs backport to 3.14 bugs and security fixes label Jul 19, 2026

bedevere-app Bot removed the needs backport to 3.13 only security fixes label Jul 19, 2026

gh-119710: Let asyncio Process.wait() finish on only process exit. by tapetersen · Pull Request #151983 · python/cpython · GitHub

Repository navigation

gh-119710: Let asyncio Process.wait() finish on only process exit. - #151983

gh-119710: Let asyncio Process.wait() finish on only process exit.#151983
kumaraditya303 merged 6 commits into
python:mainfrom
tapetersen:gh-119710-subprocess-wait-hang

tapetersen commented Jun 23, 2026

Uh oh!

python-cla-bot Bot commented Jun 23, 2026 •
edited
Loading

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

kumaraditya303 commented Jul 19, 2026 •
edited
Loading

Uh oh!

Uh oh!

Uh oh!

miss-islington-app Bot commented Jul 19, 2026

Uh oh!

bedevere-app Bot commented Jul 19, 2026

Uh oh!

bedevere-app Bot commented Jul 19, 2026

Uh oh!

bedevere-app Bot commented Jul 19, 2026

Uh oh!

tapetersen commented Jul 19, 2026

Uh oh!

Reviewers

Uh oh!

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

gh-119710: Let asyncio Process.wait() finish on only process exit. by tapetersen · Pull Request #151983 · python/cpython · GitHub

Repository navigation

gh-119710: Let asyncio Process.wait() finish on only process exit. - #151983

gh-119710: Let asyncio Process.wait() finish on only process exit.#151983kumaraditya303 merged 6 commits intopython:mainpython/cpython:mainfrom tapetersen:gh-119710-subprocess-wait-hangtapetersen/cpython:gh-119710-subprocess-wait-hangCopy head branch name to clipboard

Conversation

tapetersen commented Jun 23, 2026

gh-119710: Let asyncio Process.wait() finish on only process exit

Uh oh!

python-cla-bot Bot commented Jun 23, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

kumaraditya303 commented Jul 19, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

Uh oh!

miss-islington-app Bot commented Jul 19, 2026

Uh oh!

bedevere-app Bot commented Jul 19, 2026

Uh oh!

bedevere-app Bot commented Jul 19, 2026

Uh oh!

bedevere-app Bot commented Jul 19, 2026

Uh oh!

tapetersen commented Jul 19, 2026

Uh oh!

Reviewers

Uh oh!

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

gh-119710: Let asyncio Process.wait() finish on only process exit.#151983
kumaraditya303 merged 6 commits into
python:mainfrom
tapetersen:gh-119710-subprocess-wait-hang

python-cla-bot Bot commented Jun 23, 2026 •
edited
Loading

kumaraditya303 commented Jul 19, 2026 •
edited
Loading