【Python】进程间共享实例

#练习：进程间共享实例
import time,os
import random
from multiprocessing import Pool,Value,Lock,Manager
from multiprocessing.managers import BaseManager

class MyManager(BaseManager):
    pass

def Manager():
    m=MyManager()
    m.start()
    return m

class Counter(object):
    def __init__(self,initval=0):
        self.val=Value("i",initval)
        self.lock=Lock()
    def increment(self):
        with self.lock:
            self.val.value+=1
    def value(self):
        with self.lock:
            return self.val.value

MyManager.register("Counter",Counter)

def long_time_task(name,counter):
    time.sleep(0.2)
    print "run task %s (%s)...\n" %(name,os.getpid())
    start=time.time()
    for i in range(50):
        time.sleep(0.01)
        #进程间共享实例
        counter.increment()
    end=time.time()
    print "task %s runs %0.2f seconds." %(name,(end-start))

if __name__=="__main__":
    manager=Manager()
    counter=manager.Counter(0)
    print  "Parent process %s." % os.getpid()
    p=Pool(5)
    for i in range(5):
        p.apply_async(long_time_task,args=(str(i),counter))
    print "Waiting for all subprocesses done..."
    p.close()
    p.join()
    print "All subprocesses done."
    print counter.value()