Python use timeout for subprocess with Popen

Question

Im running the following script with popen

process = subprocess.Popen(['python', 'solver.py', 'newsudoku.csp', '-i', 'arc'], stdout=subprocess.PIPE)
out, err = process.communicate()

I need to process the output that is being stored in the out variable

thing is this script varies in the time of its execution, and I need to kill it if it goes past 60 seconds. I know that python 3 has timeout for check_call, but the other script im running is in python 2.7

So how could I count 60 seconds and then kill the subprocess? ideally doing something else as well if this happens (adding 1 to a counter)

Answer 1

You can use the timeout or waitmax commands to set a time limit on the process you are running with Popen. For instance, to run a tail -f command for a maximum of 10 seconds -

import subprocess
process=subprocess.Popen(['timeout' ,'10', 'tail', '-f', '/var/log/syslog'], stdout=subprocess.PIPE)
out,err = process.communicate()

print out
Apr 26 21:40:01 linubuvma CRON[49447]: (smmsp) CMD (test -x /etc/init.d/sendmail && /usr/share/sendmail/sendmail cron-msp)
Apr 26 21:45:01 linubuvma CRON[50065]: (root) CMD (command -v debian-sa1 > /dev/null && debian-sa1 1 1)
Apr 26 21:55:01 linubuvma CRON[51271]: (root) CMD (command -v debian-sa1 > /dev/null && debian-sa1 1 1)
Apr 26 22:00:01 linubuvma CRON[51871]: (smmsp) CMD (test -x /etc/init.d/sendmail && /usr/share/sendmail/sendmail cron-msp)
Apr 26 22:05:01 linubuvma CRON[52491]: (root) CMD (command -v debian-sa1 > /dev/null && debian-sa1 1 1)
Apr 26 22:09:01 linubuvma CRON[52975]: (root) CMD (  [ -x /usr/lib/php5/maxlifetime ] && [ -x /usr/lib/php5/sessionclean ] && [ -d /var/lib/php5 ] && /usr/lib/php5/sessionclean /var/lib/php5 $(/usr/lib/php5/maxlifetime))
Apr 26 22:15:01 linubuvma CRON[53707]: (root) CMD (command -v debian-sa1 > /dev/null && debian-sa1 1 1)
Apr 26 22:17:01 linubuvma CRON[53951]: (root) CMD (   cd / && run-parts --report /etc/cron.hourly)
Apr 26 22:20:01 linubuvma CRON[54311]: (smmsp) CMD (test -x /etc/init.d/sendmail && /usr/share/sendmail/sendmail cron-msp)
Apr 26 22:25:01 linubuvma CRON[54937]: (root) CMD (command -v debian-sa1 > /dev/null && debian-sa1 1 1)

The tail commands terminated exactly after 10 seconds.

Answer 2

you can also do something like this in python 3.7.4:

p1 = subprocess.Popen(['python', 'solver.py', 'newsudoku.csp', '-i', 'arc'], stderr = subprocess.PIPE) 
    try:
        outs, errs = p1.communicate(timeout=60) # will raise error and kill any process that runs longer than 60 seconds
    except subprocess.TimeoutExpired as e:
        p1.kill()
        outs, errs = p1.communicate()
        print(outs)
        print(errs)