[New-bugs-announce] [issue40550] Popen.terminate fails with ProcessLookupError under certain conditions

[Alexander Overvoorde]

New submission from Alexander Overvoorde <overv161 at gmail.com>:

The following program frequently raises a ProcessLookupError exception when calling proc.terminate():

```
import threading
import subprocess
import multiprocessing

proc = subprocess.Popen(["sh", "-c", "exit 0"])

q = multiprocessing.Queue()

def communicate_thread(proc):
    proc.communicate()

t = threading.Thread(target=communicate_thread, args=(proc,))
t.start()

proc.terminate()

t.join()
```

I'm reproducing this with Python 3.8.2 on Arch Linux by saving the script and rapidly executing it like this:

$ bash -e -c "while true; do python3 test.py; done

The (unused) multiprocessing.Queue seems to play a role here because the problem vanishes when removing that one line.

----------
components: Library (Lib)
messages: 368370
nosy: Alexander Overvoorde
priority: normal
severity: normal
status: open
title: Popen.terminate fails with ProcessLookupError under certain conditions
type: behavior
versions: Python 3.8

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue40550>
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