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gh-94182: run the PidfdChildWatcher on the running loop#94184

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gvanrossum merged 33 commits intopython:mainfrom
graingert:run-pidfdchildwatcher-on-the-running-loop
Oct 8, 2022
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gh-94182: run the PidfdChildWatcher on the running loop#94184
gvanrossum merged 33 commits intopython:mainfrom
graingert:run-pidfdchildwatcher-on-the-running-loop

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@graingert graingert commented Jun 23, 2022 •
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Lib/test/test_asyncio/test_subprocess.py Outdated


class GenericWatcherTests:
class GenericWatcherTests(test_utils.TestCase):
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this test wasn't enabled?

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@graingert graingert Jul 19, 2022

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I split this fix out, so this PR is easier to review: #95009

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graingert commented Jun 23, 2022
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Lib/test/test_asyncio/test_subprocess.py Outdated

async def execute():
watcher = mock.create_authspec(asyncio.AbstractChildWatcher)
watcher.is_active.return_value = False
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@graingert graingert Jun 24, 2022 •
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this was patching the wrong attribute - asyncio calls asyncio.get_child_watcher().__enter__().is_active()

graingert and others added 2 commits June 24, 2022 09:10
@graingert
check that asyncio.set_event_loop() was not called
6e56155 
otherwise it invalidates test_create_subprocess_with_pidfd
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📜🤖 Added by blurb_it.
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@graingert graingert marked this pull request as ready for review June 24, 2022 08:50
@graingert graingert requested review from 1st1 and asvetlov as code owners June 24, 2022 08:50
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graingert commented Jul 6, 2022

@asvetlov can I get a review on this please?

@gvanrossum gvanrossum self-requested a review as a code owner October 7, 2022 18:55
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LGTM. We'll probably merge this ASAP.

Lib/test/test_asyncio/test_subprocess.py


@functools.cache
def _has_pidfd_support():
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This same function is also introduced by @kumaraditya303's PR GH-98024 (which uses PidfdChildWatcher when supported). I propose to refactor things so that everything uses Kumar's version. We can do that in Kumar's PR once this PR is merged.

Lib/asyncio/unix_events.py
def _do_wait(self, pid):
pidfd, callback, args = self._callbacks.pop(pid)
self._loop._remove_reader(pidfd)
def _do_wait(self, pid, pidfd, callback, args):
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Curious why we can't pass the loop as an argument as well? (Though maybe that creates an unhealthy self-reference to the loop.)

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gvanrossum commented Oct 7, 2022

(Waiting for @1st1 review and passing tests.)

@gvanrossum gvanrossum mentioned this pull request Oct 7, 2022
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gvanrossum commented Oct 7, 2022

Not sure what's wrong with the docs build.

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1st1 commented Oct 7, 2022

Not sure what's wrong with the docs build.

I've fixed it.

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1st1 commented Oct 7, 2022

I've fixed it.

Reverted the "fix" because apparently it was caused by an unrelated commit in main.

@JelleZijlstra JelleZijlstra self-assigned this Oct 7, 2022
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JelleZijlstra commented Oct 7, 2022

I can take care of getting CI green and hitting the merge button here.

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1st1 commented Oct 7, 2022

I can take care of getting CI green and hitting the merge button here.

Please do. You might need to rebase this PR to the latest main.

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gvanrossum commented Oct 8, 2022

The macOS build hit some GitHub Actions limit. I'm going to merge without waiting for it.

@gvanrossum gvanrossum merged commit 3d8b224 into python:main Oct 8, 2022
carljm added a commit to carljm/cpython that referenced this pull request Oct 8, 2022
@carljm
Merge branch 'main' into typewatch
d67d6fd 
* main:
  pythongh-68686: Retire eptag ptag scripts (python#98064)
  pythongh-97922: Run the GC only on eval breaker (python#97920)
  GitHub Workflows security hardening (python#96492)
  Add `@ezio-melotti` as codeowner for `.github/`. (python#98079)
  pythongh-97913 Docs: Add walrus operator to the index (python#97921)
  [doc] Fix broken links to C extensions accelerating stdlib modules (python#96914)
  pythongh-97822: Fix http.server documentation reference to test() function (python#98027)
  pythongh-91052: Add PyDict_Unwatch for unwatching a dictionary (python#98055)
  pythonGH-98023: Change default child watcher to PidfdChildWatcher on supported systems (python#98024)
  pythonGH-94182: Run the PidfdChildWatcher on the running loop (python#94184)
carljm added a commit to carljm/cpython that referenced this pull request Oct 9, 2022
@carljm
Merge branch 'main' into urllibnonet
132c32e 
* main: (5519 commits)
  Minor edits to the Descriptor HowTo Guide (pythonGH-24901)
  Fix link to Lifecycle of a Pull Request in CONTRIBUTING (python#98102)
  pythonGH-94597: deprecate `SafeChildWatcher`, `FastChildWatcher` and `MultiLoopChildWatcher` child watchers  (python#98089)
  Auto-cancel old builds when new commit pushed to branch (python#98009)
  pythongh-95011: Migrate syslog module to Argument Clinic (pythonGH-95012)
  pythongh-68686: Retire eptag ptag scripts (python#98064)
  pythongh-97922: Run the GC only on eval breaker (python#97920)
  GitHub Workflows security hardening (python#96492)
  Add `@ezio-melotti` as codeowner for `.github/`. (python#98079)
  pythongh-97913 Docs: Add walrus operator to the index (python#97921)
  [doc] Fix broken links to C extensions accelerating stdlib modules (python#96914)
  pythongh-97822: Fix http.server documentation reference to test() function (python#98027)
  pythongh-91052: Add PyDict_Unwatch for unwatching a dictionary (python#98055)
  pythonGH-98023: Change default child watcher to PidfdChildWatcher on supported systems (python#98024)
  pythonGH-94182: Run the PidfdChildWatcher on the running loop (python#94184)
  pythongh-92886: make test_ast pass with -O (assertions off) (pythonGH-98058)
  pythongh-92886: make test_coroutines pass with -O (assertions off) (pythonGH-98060)
  pythongh-57179: Add note on symlinks for os.walk (python#94799)
  pythongh-94808: Fix regex on exotic platforms (python#98036)
  pythongh-90085: Remove vestigial -t and -c timeit options (python#94941)
  ...
mpage pushed a commit to mpage/cpython that referenced this pull request Oct 11, 2022
@graingert @1st1
@JelleZijlstra @mpage
pythonGH-94182: Run the PidfdChildWatcher on the running loop (python…
6cd489d 
…#94184)

There is no reason for this watcher to be attached to any particular loop.
This should make it safe to use regardless of the lifetime of the event loop running in the main thread
(relative to other loops).

Co-authored-by: Yury Selivanov <[email protected]>
Co-authored-by: Jelle Zijlstra <[email protected]>
bdraco added a commit to bdraco/home-assistant that referenced this pull request Feb 12, 2023
@bdraco
Use PidfdChildWatcher by default when available
29f4931 
This is a backport from cpython 3.12

https://docs.python.org/3/library/asyncio-policy.html
> PidfdChildWatcher is a “Goldilocks” child watcher implementation. It doesn’t require signals or threads, doesn’t interfere with any processes launched outside the event loop, and scales linearly with the number of subprocesses launched by the event loop. The main disadvantage is that pidfds are specific to Linux, and only work on recent (5.3+) kernels.

python/cpython#98024
There are some additional fixes in cpython 3.12
in python/cpython#94184
when there is no event loop running in the main thread
but this is not a problem we have
@bdraco bdraco mentioned this pull request Feb 12, 2023
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balloob pushed a commit to home-assistant/core that referenced this pull request Feb 12, 2023
@bdraco
Use PidfdChildWatcher by default when available (#87951)
d1e1734 
This is a backport from cpython 3.12

https://docs.python.org/3/library/asyncio-policy.html
> PidfdChildWatcher is a “Goldilocks” child watcher implementation. It doesn’t require signals or threads, doesn’t interfere with any processes launched outside the event loop, and scales linearly with the number of subprocesses launched by the event loop. The main disadvantage is that pidfds are specific to Linux, and only work on recent (5.3+) kernels.

python/cpython#98024
There are some additional fixes in cpython 3.12
in python/cpython#94184
when there is no event loop running in the main thread
but this is not a problem we have
AlePerla pushed a commit to AlePerla/homeassistant_core that referenced this pull request Feb 17, 2023
@bdraco @AlePerla
Use PidfdChildWatcher by default when available (home-assistant#87951)
638c431 
This is a backport from cpython 3.12

https://docs.python.org/3/library/asyncio-policy.html
> PidfdChildWatcher is a “Goldilocks” child watcher implementation. It doesn’t require signals or threads, doesn’t interfere with any processes launched outside the event loop, and scales linearly with the number of subprocesses launched by the event loop. The main disadvantage is that pidfds are specific to Linux, and only work on recent (5.3+) kernels.

python/cpython#98024
There are some additional fixes in cpython 3.12
in python/cpython#94184
when there is no event loop running in the main thread
but this is not a problem we have
@graingert graingert deleted the run-pidfdchildwatcher-on-the-running-loop branch October 11, 2023 15:17
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