python多進程管理DEMO

在使用python的時候，為了提高效率，也為了避開python的GIL限制充分發揮多核的優勢，經常會使用multiprocessing模組來實現多進程處理。效率會有很大的提升，但這樣一來就引入的多進程管理的問題，比如：假定父進程設定的是啟動5個子進程，但在實際運行中因為種種原因有3個子進程異常退出，此時該怎麼辦？運行過程中想退出整個程式的運行，怎麼退出更合理，更優雅？
下面的python代碼簡單展示了如何使用signal來處理multiprocessing協作。

# -*- coding: utf-8 -*-'''Created on 2012-10-14 19:50@summary:  multiprocessing coordinate demo@author: JerryKwan'''from multiprocessing import Event, Processimport signalimport timeSUBPROCESSES = []WORKERS = []EXIT = Event()def exit_handler(signum, frame):    print "signal handler called with signal ", signum, " ", WORKERS, " ", frame    EXIT.set()    time.sleep(1)    for w in WORKERS:        print "begin to invoke stop_main_loop"        w.stop_main_loop()signal.signal(signal.SIGTERM, exit_handler)signal.signal(signal.SIGINT, exit_handler)class Worker(object):    """docstring for Worker"""    def __init__(self, arg = "default arg"):        super(Worker, self).__init__()        self.arg = arg        self.be_exit = Event()        self.be_exit.clear()    def stop_main_loop(self):        print "stop_main_loop invoked"        self.be_exit.set()    def main_loop(self):        print "main_loop invoked"        while not self.be_exit.is_set():            print "do something"            try:                time.sleep(1)            except Exception, e:                print "exception occured, ", e        print "exit from main_loop"def do_work(worker):    print "do_work invoked"    worker.main_loop()def create_subprocess():    '''    @summary: create subprocess    @return: (worker, process)    '''    w = Worker()    p = Process(target = do_work, args = (w,))    p.daemon = True    return (w, p)def main():    process_num = 2    for i in xrange(process_num):        w, p = create_subprocess()        WORKERS.append(w)        SUBPROCESSES.append(p)    # signal.signal(signal.SIGTERM, exit_handler)    # signal.signal(signal.SIGINT, exit_handler)    # start    for p in SUBPROCESSES:        p.start()    # for p in SUBPROCESSES:    #     p.join()    print "monitor subprocess"    while not EXIT.is_set():        for i in xrange(len(SUBPROCESSES)):            p = SUBPROCESSES[i]            if not p.is_alive():                # create new process to replace the dead one                print "%d process is dead, so i will create a new one to relace it." %i                w, p = create_subprocess()                WORKERS[i] = w                SUBPROCESSES[i] = p                p.start()        time.sleep(1)    print "main process exit"    # wait subprocess exit    # for i in xrange(process_num):    #     whileif __name__ == '__main__':    main()