subprocess-popen-preexec-fn / W1509

Message emitted:

Using preexec_fn keyword which may be unsafe in the presence of threads

Description:

The preexec_fn parameter is not safe to use in the presence of threads in your application. The child process could deadlock before exec is called. If you must use it, keep it trivial! Minimize the number of libraries you call into. See https://docs.python.org/3/library/subprocess.html#popen-constructor

Problematic code:

import subprocess


def foo():
    pass


subprocess.Popen(preexec_fn=foo)  # [subprocess-popen-preexec-fn]

Correct code:

import subprocess

subprocess.Popen()

Created by the stdlib checker.