python - Kill or terminate subprocess when timeout?

Question

I would like to repeatedly execute a subprocess as fast as possible. However, sometimes the process will take too long, so I want to kill it. I use signal.signal(...) like below:

ppid=pipeexe.pid
signal.signal(signal.SIGALRM, stop_handler)

signal.alarm(1)
.....
def stop_handler(signal, frame):
    print 'Stop test'+testdir+'for time out'
    if(pipeexe.poll()==None and hasattr(signal, "SIGKILL")):
         os.kill(ppid, signal.SIGKILL)
         return False

but sometime this code will try to stop the next round from executing. Stop test/home/lu/workspace/152/treefit/test2for time out /bin/sh: /home/lu/workspace/153/squib_driver: not found ---this is the next execution; the program wrongly stops it.

Does anyone know how to solve this? I want to stop in time not execute 1 second the time.sleep(n) often wait n seconds. I do not want that I want it can execute less than 1 second

Answer 1

You could do something like this:

import subprocess as sub
import threading

class RunCmd(threading.Thread):
    def __init__(self, cmd, timeout):
        threading.Thread.__init__(self)
        self.cmd = cmd
        self.timeout = timeout

    def run(self):
        self.p = sub.Popen(self.cmd)
        self.p.wait()

    def Run(self):
        self.start()
        self.join(self.timeout)

        if self.is_alive():
            self.p.terminate()      #use self.p.kill() if process needs a kill -9
            self.join()

RunCmd(["./someProg", "arg1"], 60).Run()

The idea is that you create a thread that runs the command and to kill it if the timeout exceeds some suitable value, in this case 60 seconds.