Best way to run a function every x seconds then kill and repeat?

Question

Say i want to do

import subprocess
subprocess.call(["foo"])

My question is, how could i run subprocess.call(["foo"]) every x seconds, then kill the process, then repeat x seconds later?

You can do an infinite while loop and sleep at the end of it — Jalo, Nov 16 '16 at 09:37
Not an answer in python, but you could use `bash`'s `timeout` — Reut Sharabani, Nov 16 '16 at 09:56
'then kill the proces' When do you want to kill the process? How long shall it run? — , Nov 16 '16 at 10:01

score 1 · Answer 1 · edited May 23 '17 at 12:30

To run a command every x seconds you can use a infinite loop and time

import os
import signal
import subprocess
import time

cmd = "python -m SimpleHTTPServer"

while True: 
    server = subprocess.Popen(cmd , stdout=subprocess.PIPE, shell=True,
                       preexec_fn=os.setsid)

    time.sleep(10)
    os.killpg(os.getpgid(server.pid), signal.SIGTERM)
    time.sleep(5)

If you don't know how to stop the process I recommend you to check https://stackoverflow.com/a/4791612/2588566

If you just want the process to run x time sleeping use a for loop instead.

I don't know what command you want to run. In this example you run a python server serving files in the current dir. It start the process, keep it running for 10 seconds, then kill the process and waits 5 seconds (So you can check it has been stopped). So you have a server running 10 seconds and a gap of 5 seconds between each execution.

Please fill the `Here goes your command` part. How would you start *and kill* a process? — , Nov 16 '16 at 10:06

score 0 · Answer 2 · 2016-11-16T10:06:09.400

subprocess.call does not return until the process foo finishes.

Run the command described by args. Wait for command to complete, then return the returncode attribute.

Use Popen instead.

import subprocess
import time

while True:
    # The process will take 10 seconds to finish, but ...
    p = subprocess.Popen(["sleep", "10"])

    # ... we kill it after 5 seconds.
    time.sleep(5)
    p.kill()

score 0 · Answer 3 · answered Nov 17 '16 at 00:40

There is a system of instructions can be done. Code does not need to set the cycle, starting from the main function, the implementation of the output and rest, and then restart the process

import time
import sys 
import os

def restart_program():
    python = sys.executable
    os.execl(python, python, * sys.argv)

if __name__ == "__main__":
    print 'start...'
    print "sleep 3s..."
    time.sleep(3)
    restart_program()

Best way to run a function every x seconds then kill and repeat?

3 Answers3