Timeout decorator

Posted on One min read

Sometimes it makes sense to end a method when a defined point in time is exceeded. The following code shows a decorator that will end any decorated function after the defined time.

    import signal
    TASK_TIMEOUT = 4

    class Timeout(Exception):
        pass

    def timed_task(method):
        def _handle_timeout(signum, frame):
            raise Timeout("Task TIMEOUT! [{} Seconds]".format(TASK_TIMEOUT))

        def timed(*args, **kw):
            signal.signal(signal.SIGALRM, _handle_timeout)
            signal.alarm(TASK_TIMEOUT)
            try:
                result = method(*args, **kw)
            finally:
                signal.alarm(0)
            return result

        return timed

To use this we have just decorate a function and whait til the exception is thrown.

    from time import sleep
    from decorators.timed_task import timed_task, TASK_TIMEOUT

    @timed_task
    def sleepyhead():
        sleep(TASK_TIMEOUT + 1)
    sleepyhead()

The cool thing about this is the signal.alarm part. This function is able to call a so called handler after a defined period of time. In this case this is the method handle_timeout wich will raise the Timeout-Exception.

    decorators.timed_task.Timeout: Task TIMEOUT! [5 Seconds]