CODEWITHSUNDEEP
pythonpython-2.7
idanshmu
idanshmu

Reputation: 5271

python 2.7 - run sub-process and terminate it if user time exceeded max time

I'm writing Python 2.7 that need to run sub-process and terminate it if the subprocess user time exceeded max time.
The definiton for user time can be found in this answer to What do 'real', 'user' and 'sys' mean in the output of time(1)?
So far I have this:

Code

from multiprocessing import Process
import time

def do_something():
    pass

def run_process_limited_time(max_seconds):

    # init Process
    p = Process(target=do_something, args=())

    # start process
    p.start()

    run_time = 0;
    sleep_time = 1;

    while 1:

        # sleep for sleep_time seconds
        time.sleep(sleep_time)

        # increase run time
        run_time += sleep_time

        # if process is not alive, we can break the loop
        if not p.is_alive():
            break

        # if process is still alive after max_seconds, kill it!
        # TBD - condition is not sufficient 
        elif run_time > max_seconds:
            p.terminate()
            break

def main():
    run_process_limited_time(10)

if __name__ == "__main__":
    main()

Question

the condition elif run_time > max_seconds is not good enough. I'd like to check that max seconds does not exceed user time only. Not sure I can do it using Process module but I'm open to new ideas.

Upvotes: 2

Views: 433

Answers (2)

Andrew Walker
Andrew Walker

Reputation: 42500

An alternative using the resource module. Handling the timeout can be achieved using the signal module. Returning results can be handled in a variety of ways, some of which are described in the multiprocessing documentation.

from multiprocessing import Process
import time
import resource
import signal

def do_something():
    import resource
    resource.setrlimit(resource.RLIMIT_CPU, (1,1))
    def f(signo, stackframe):
        raise Exception('stop')
    signal.signal(signal.SIGXCPU, f)
    try:
        while 1:
            print 'hello'
    except:
        print 'aborted'

def run_process_limited_time(function):

    # init Process
    p = Process(target=function, args=())

    # start process
    p.start()

    p.join(2)
    p.terminate()


if __name__ == "__main__":
    run_process_limited_time(do_something)

Upvotes: 1

Nafiul Islam
Nafiul Islam

Reputation: 82570

This is because you're using an elif statement where you should be using an if statement:

from multiprocessing import Process
import time


def do_something():
    while True:
        time.sleep(100)


def run_process_limited_time(max_seconds):

    # init Process
    p = Process(target=do_something, args=())

    # start process
    p.start()

    run_time = 0
    sleep_time = 1

    while True:
        time.sleep(sleep_time)
        run_time += sleep_time
        if not p.is_alive():
            break

        if run_time > max_seconds:
            print "Process was terminated, due to exceeding max time"
            p.terminate()
            break


def main():
    run_process_limited_time(10)

if __name__ == "__main__":
    main()

Try the above, the process should be terminated.

Upvotes: 1

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