Timeout on subprocess readline in Python

Question

I have a small issue that I\'m not quite sure how to solve. Here is a minimal example:

What I have

scan_process = subprocess.Popen(command, stdout=su         


        

Answer 1

I used something a bit more general in Python (if I remember correctly, also pieced together from Stack Overflow questions, but I cannot recall which ones).

import thread
from threading import Timer

def run_with_timeout(timeout, default, f, *args, **kwargs):
    if not timeout:
        return f(*args, **kwargs)
    try:
        timeout_timer = Timer(timeout, thread.interrupt_main)
        timeout_timer.start()
        result = f(*args, **kwargs)
        return result
    except KeyboardInterrupt:
        return default
    finally:
        timeout_timer.cancel()

Be warned, though. This uses an interrupt to stop whatever function you give it. This might not be a good idea for all functions and it also prevents you from closing the program with Ctrl + C during the timeout (i.e. Ctrl + C will be handled as a timeout).

You could use this and call it like:

scan_process = subprocess.Popen(command, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
while(some_criterium):
    line = run_with_timeout(timeout, None, scan_process.stdout.readline)
    if line is None:
        break
    else:
        some_criterium = do_something(line)

It might be a bit overkill, though. I suspect there is a simpler option for your case that I don't know.