Description

assignee = None
closed_at = None
created_at = <Date 2019-11-21.21:43:43.189>
labels = ['type-feature', 'library', '3.9']
title = 'Popen should use pidfd_open to implement a non-busy wait'
updated_at = <Date 2019-11-21.22:20:50.812>
user = 'https://github.com/SpecLad'

activity = <Date 2019-11-21.22:20:50.812>
actor = 'SpecLad'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2019-11-21.21:43:43.189>
creator = 'SpecLad'
dependencies = []
files = []
hgrepos = []
issue_num = 38888
keywords = []
message_count = 3.0
messages = ['357222', '357223', '357225']
nosy_count = 4.0
nosy_names = ['gregory.p.smith', 'vstinner', 'benjamin.peterson', 'SpecLad']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue38888'
versions = ['Python 3.9']

Activity

1. SpecLad commented on Nov 21, 2019

   

   SpecLadmannequin

   on Nov 21, 2019

   MannequinAuthor

   More actions

   Popen.wait(timeout) is currently implemented on Unix-like systems using a busy wait, since the waitpid system call doesn't have a timeout argument.

   On Linux, it's now possible to do better than that. You can create a PID file descriptor using pidfd_create and poll that descriptor with the specified timeout. Popen.wait should make use of that.
2. SpecLad

   added

   3.9 (EOL)end of lifeend of life

   stdlibStandard Library Python modules in the Lib/ directoryStandard Library Python modules in the Lib/ directory

   type-featureA feature request or enhancementA feature request or enhancement

   on Nov 21, 2019
3. vstinner commented on Nov 21, 2019

   

   vstinner

   on Nov 21, 2019

   Member

   More actions

   os.pidfd_open() was added to Python 3.9. Do you mean pidfd_open()?
4. SpecLad commented on Nov 21, 2019

   

   SpecLadmannequin

   on Nov 21, 2019

   MannequinAuthor

   More actions

   Right, of course. I keep confusing it with timerfd_create.
5. SpecLad

   changed the title [-]Popen should use pidfd_create to implement a non-busy wait[/-] [+]Popen should use pidfd_open to implement a non-busy wait[/+] on Nov 21, 2019
6. ezio-melotti

   transferred this issue fromon Apr 10, 2022
7. giampaolo commented on Jan 19, 2026

   

   giampaolo

   on Jan 19, 2026

   Contributor

   More actions

   Hi. Since I recently implemented this in psutil (giampaolo/psutil#2706), I decided to give this a try and port this change to the subprocess module. I created a PR which uses pidfd_open() on Linux and also adds support for macOS and BSD by using kqueue(): #144047.

   Reacted by Victor Stinner
8. vstinner

   added a commit that references this issue on Jan 28, 2026

   gh-83069: Use efficient event-driven `subprocess.Popen.wait()` on Lin…

   9b154ab
9. vstinner

   closed this as completedon Jan 28, 2026
10. vstinner commented on Jan 28, 2026

    

    vstinner

    on Jan 28, 2026

    Member

    More actions

    The feature is now implemented, I close the issue.
11. thunder-coding

    added a commit that references this issue on Feb 15, 2026

    pythongh-83069: Use efficient event-driven `subprocess.Popen.wait()` …

    368281f
12. gpshead

    added 2 commits that reference this issue on Jul 29, 2026

    gh-154836: Fix Popen.wait() with very large timeouts on the pidfd/kqu…

    11d0da5

    [3.15] gh-154836: Fix Popen.wait() with very large timeouts on the pi…

    dd2714d
13. mbeijen

    added a commit that references this issue on Aug 14, 2026

    pythongh-154836: Fix Popen.wait() with very large timeouts on the pid…

    8377ae7

Issue actions