How do I close the stdout-pipe when killing a process started with python subprocess Popen?

Question

I wonder if it is possible to shut down the communication pipe when killing a subprocess started in a different thread. If I do not call communicate() then kill() will work as e

Answer 1

I think the problem is that process.kill() only kills the immediate child process (bash), not the sub-processes of the bash script.

The problem and solution are described here:

• http://www.doughellmann.com/PyMOTW/subprocess/#process-groups-sessions
• How to terminate a python subprocess launched with shell=True

Use Popen(..., preexec_fn=os.setsid) to create a process group and os.pgkill to kill the entire process group. eg

import os
import signal
import subprocess
import time
from threading import Thread

process = None

def executeCommand(command, runCommand):
    Thread(target=runCommand, args=(command,)).start()

def runCommand(command):
    global process
    args = command.strip().split()
    process = subprocess.Popen(
        args, shell=False, stdout=subprocess.PIPE, preexec_fn=os.setsid)

    for line in process.communicate():
        if line:
            print "process:", line,

if __name__ == '__main__':
    executeCommand("./ascript.sh", runCommand)
    time.sleep(1)
    os.killpg(process.pid, signal.SIGKILL)

---

$ time python poc.py 
process: sleeping five

real    0m1.051s
user    0m0.032s
sys 0m0.020s