subprocess.run() hangs when nested in subprocess.Popen() context

[hundeboll]

Bug report

Bug description:

I'd expect this snippet to raise a subprocess.CalledProcessError exception, but it just hangs instead:

import subprocess

with subprocess.Popen(["sleep", "infinity"]) as process:
    subprocess.run(["false"], check=True)
    process.terminate()

The same functionality without the manged context does raise as expected:

import subprocess

process = subprocess.Popen(["sleep", "infinity"])
subprocess.run(["false"], check=True)
process.terminate()

The nested call to subprocess.run() returns as expected, when the called process doesn't fail:

import subprocess

with subprocess.Popen(["sleep", "infinity"]) as process:
    subprocess.run(["true"], check=True)
    process.terminate()

CPython versions tested on:

3.13.13, 3.14.5, 3.15.0b2

Operating systems tested on:

Linux

[vadmium]

I think this is as intended. The documentation says “on exit, standard file descriptors are closed, and the process is waited for.”

It might make more sense for you to terminate the sleep process when the nested code fails:

with process:
    try:
        subprocess.run(['false'], check=True)
    finally:
        process.terminate()  # Even when an exception is raised