11

Possible Duplicate:
Timeout on a Python function call

I want to implement that when the function took more than 90 seconds to complete it should return immediately when timeout. Is there any way to achieve that?

def abc(string): import re if re.match('some_pattern', string): return True else: return False abc('some string to match')

Edited

Please download this test file. I have created a thread class and raise an exception within thread if timeout error occur. But thread is still alive because it prints i am still alive :) even after exception. Why an exception does not force the thread to stop??

Improve this question
2
  • 2
    This kind of question usually gets answers involving threads, signal.alarm(), signal.setitmer() etc. Be careful with those answers -- they probably rely on Python exceptions being thrown, but I doubt a Python exception can interrupt re.match(). (Not sure about the right answer. Maybe use a subprocess, and kill it after 90 seconds.) Commented Nov 28, 2011 at 16:44
  • @aix: While the linked question is very similar, none of the answers there is really applicable here. Only the checked answer would work at all, but it would leave the stalled function running in the background and consuming CPU time. That's why I'm not voting to close. Commented Nov 28, 2011 at 18:09

2 Answers 2

Reset to default
6

I've edited my post to use jcollado's idea which is simpler.

The multiprocessing.Process.join method has a timeout argument which you can use like this:

import multiprocessing as mp import time import logging import re logger = logging.getLogger(__name__) def abc(string, result, wait = 0): time.sleep(wait) result.put(bool(re.match('some_pattern', string))) if __name__ == '__main__': logging.basicConfig(level = logging.DEBUG, format = '%(asctime)s: %(message)s', datefmt = '%H:%M:%S', ) result = mp.Queue() proc = mp.Process(target = abc, args = ('some_pattern to match', result)) proc.start() proc.join(timeout = 5) if proc.is_alive(): proc.terminate() else: logger.info(result.get()) proc = mp.Process(target = abc, args = ('some string to match', result, 20)) proc.start() proc.join(timeout = 5) if proc.is_alive(): logger.info('Timed out') proc.terminate() else: logger.info(result.get())

yields

12:07:59: True 12:08:04: Timed out

Note that you get the "Timed out" message in 5 seconds, even though abc('some string',20) would have taken around 20 seconds to complete.

Improve this answer
Sign up to request clarification or add additional context in comments.

8 Comments

Will the operation in the subprocess be interrupted, or will it continue to consume CPU time?
@Sven: Your comment was probably before my edit -- pool.terminate will interrupt the subprocess.
@SvenMarnach, Docs for Pool.terminate() say "Stops the worker processes immediately without completing outstanding work. When the pool object is garbage collected terminate() will be called immediately." and Process.terminate() says "Terminate the process. On Unix this is done using the SIGTERM signal; on Windows TerminateProcess() is used. Note that exit handlers and finally clauses, etc., will not be executed." so I think you can assume it does as needed here.
@Duncan: Thanks. As unutbu said, my comment was before the edit.
@unutbu i tried your approach i works fine on simple function but when i used it in my main program o got following exception Traceback (most recent call last): File "C:\Python27\lib\threading.py", line 552, in __bootstrap_inner self.run() File "C:\Python27\lib\threading.py", line 505, in run self.__target(*self.__args, **self.__kwargs) File "C:\Python27\lib\multiprocessing\pool.py", line 313, in _handle_tasks put(task) PicklingError: Can't pickle <type 'thread.lock'>: attribute lookup thread.lock failed.
|
0

One way to handle this is to put this task into a thread, and use a watchdog to kill it after 90 seconds have passed.

Here's a recipe at ActiveState.

Edit: Obviously, the recipe by itself is not the complete solution. You would either have a watchdog thread that checked every x seconds if the worker thread was done, or you would go to an event framework like Michael Ford's simple event framework.

Improve this answer

2 Comments

that is a good recipe please wait untill i implement it. Thanks for help.
This recipe is completely unapplicable for the given problem. It relies on the worker thread polling some flag. How would you make re.match() poll a flag? (-1)

Start asking to get answers

Find the answer to your question by asking.

Ask question

Explore related questions

See similar questions with these tags.