Python Popen with timeout

gistfile1.py

import os
import signal
import subprocess
import threading

class AsyncPopen(threading.Thread):

    def __init__(self, command, stdin=None, **kwargs):
        self.command = command
        self.stdin = stdin
        self.stdout = None
        self.stderr = None
        kwargs['stdin'] = subprocess.PIPE
        kwargs['stdout'] = subprocess.PIPE
        kwargs['stderr'] = subprocess.PIPE
        kwargs['preexec_fn'] = os.setpgrp
        self.kwargs = kwargs
        threading.Thread.__init__(self)

    def run(self):
        self.proc = subprocess.Popen(self.command, **self.kwargs)
        self.stdout, self.stderr = self.proc.communicate(self.stdin)

    def wait(self, timeout):
        self.join(timeout)
        if self.proc.returncode is None:
            os.killpg(self.proc.pid, signal.SIGTERM)
            self.proc.wait()

ap = AsyncPopen(['bash', '-c', 'echo bar; sleep 2; echo foo'])
ap.start()
ap.wait(1)
assert ap.stdout == 'bar\n'
assert ap.stderr == ''
assert not ap.is_alive()