Today I often use multiprocessing module, and i needed some template to write scripts a little faster..
Hope it will be useful to you.
#!/usr/bin/env python #Multiprocessing template from multiprocessing import Pool,cpu_count,active_children,Lock import signal from time import sleep import sys class TimeoutException(Exception): """ Simple Exception to be called on timeouts. """ pass def _timeout(signum, frame): """ Raise an TimeoutException. This is intended for use as a signal handler. The signum and frame arguments passed to this are ignored. """ # Raise TimeoutException with system default timeout message raise TimeoutException() # Set the handler for the SIGALRM signal: signal.signal(signal.SIGALRM, _timeout) # Send the SIGALRM signal in 10 seconds: # Multiprocessing with KeyboardInterrupt def init_worker(): signal.signal(signal.SIGINT, signal.SIG_IGN) def $$somefunc$$($$args$$): try: signal.alarm(5) #timeout exception $$do something$$ return $$some data$$ except Exception: pass except TimeoutException: print 'It timed out!' finally: signal.alarm(0) def main(): try: def cb(data): if data: $$do something with returned data$$ pool = Pool(processes=cpu_count()*10, initializer=init_worker) #processes = CPU*10 = 40 (if 4 CPUs) for i in $$some_list$$: pool.apply_async($$somefunc$$, ($$args$$,), callback=cb) #callback function defined above pool.close() #wait for worker processes completes job while len(active_children()) > 1: sleep(0.5) pool.join() return # ^C will kill all running processes and return to main function except KeyboardInterrupt: print " Terminating..." pool.close() pool.terminate() return else: print sys.exc_info() return
By the way, instead of callback() function, shared memory can be managed by Manager() module.
Manager module type support: list, dict, Namespace, Lock, RLock, Semaphore, BoundedSemaphore, Condition, Event, Queue, Value and Array.
Set as global variable:
manager = Manager.list() lock = Lock() #pass this lock to worker process
Call in running process:
with lock: manager.append($$something$$) #the lock is necessary, because of two processes can try to read the same value before editing it.
Maybe it's a mess for you, but maybe it will help.
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