Question

I want to use subprocess to run a program and I need to limit the execution time. For example, I want to kill it if it runs for more than 2 seconds.

For common programs, kill() works well. But if I try to run /usr/bin/time something, kill() can’t really kill the program.

My code below seems doesn’t work well. The program is still running.

import subprocess
import time

exec_proc = subprocess.Popen("/usr/bin/time -f \"%e\\n%M\" ./son > /dev/null", stdout = subprocess.PIPE, stderr = subprocess.STDOUT, shell = True)

max_time = 1
cur_time = 0.0
return_code = 0
while cur_time <= max_time:
    if exec_proc.poll() != None:
        return_code = exec_proc.poll()
        break
    time.sleep(0.1)
    cur_time += 0.1

if cur_time > max_time:
    exec_proc.kill()

Answer 1

do it like so in your command line:

perl -e 'alarm shift @ARGV; exec @ARGV' <timeout> <your_command>

this will run the command <your_command> and terminate it in <timeout> second.

a dummy example :

# set time out to 5, so that the command will be killed after 5 second 
command = ['perl', '-e', "'alarm shift @ARGV; exec @ARGV'", "5"]

command += ["ping", "www.google.com"]

exec_proc = subprocess.Popen(command)

or you can use the signal.alarm() if you want it with python but it’s the same.