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gh-83069: Use efficient event-driven subprocess.Popen.wait() on Linux / macOS / BSD - #144047
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vstinner merged 68 commits intoJan 28, 2026
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Thanks for the review @vstinner. I addressed your comments. |
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LGTM. Thanks for the updates!
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Whops! I fixed the remaining bare assert statements. |
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@gpshead: Do you want to double check the change? |
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In the hope of adding BSD / macOS support for asyncio in the future, I have opened #144211. |
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Merged, thank you for this nice optimization! |
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thunder-coding
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…on Linux / macOS / BSD (python#144047)
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This patch replaces the busy-loop mechanism used by subprocess.Popen.wait() on Linux, BSD, and macOS when a timeout is specified:
The kernel wakes us up exactly when the PID terminates or the timeout expires. If the fast-wait mechanisms is not available or fails (e.g. "too many open files"), the function falls back to the traditional busy loop. A similar approach was recently implemented in psutil (see giampaolo/psutil#2706). While working on that change, I noticed that the subprocess module used essentially the same busy-loop strategy, which motivated this proposal.
EDIT: I wrote a blog post about this: https://gmpy.dev/blog/2026/event-driven-process-waiting