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使用Condition对象可以在某些事件触发或者达到特定的条件后才处理数据,Condition除了具有Lock对象的acquire方法和release方法外,还有wait方法、notify方法、notifyAll方法等用于条件处理。

threading.Condition([lock]):创建一个condition,支持从外界引用一个Lock对象(适用于多个condtion共用一个Lock的情况),默认是创建一个新的Lock对象。

acquire()/release():获得/释放 Lock

wait([timeout]):线程挂起,直到收到一个notify通知或者超时(可选的,浮点数,单位是秒s)才会被唤醒继续运行。wait()必须在已获得Lock前提下才能调用,否则会触发RuntimeError。调用wait()会释放Lock,直至该线程被Notify()、NotifyAll()或者超时线程又重新获得Lock.

notify(n=1):通知其他线程,那些挂起的线程接到这个通知之后会开始运行,默认是通知一个正等待该condition的线程,最多则唤醒n个等待的线程。notify()必须在已获得Lock前提下才能调用,否则会触发RuntimeError。notify()不会主动释放Lock。

notifyAll(): 如果wait状态线程比较多,notifyAll的作用就是通知所有线程(这个一般用得少)

举例:

import threading

import time

L=[]

class boy(threading.Thread):

def __init__(self,cond,name = 'A boy'):

threading.Thread.__init__(self)

self.cond = cond

self.name = name

def run(self):

time.sleep(1)

'''boy start conversation, make sure

the girl thread stared before send notify'''

self.cond.acquire()

print self.name + ':Hello pretty~,I miss you\n'

self.cond.notify()

self.cond.wait()

print self.name + ':like moth missing fire\n'

self.cond.notify()

self.cond.wait()

print self.name + ':and I bought a gift for you in the list L\n'

L.append('channel5')

self.cond.notify()

self.cond.release()

class girl(threading.Thread):

def __init__(self,cond,name = 'A girl'):

threading.Thread.__init__(self)

self.cond = cond

self.name = name

def run(self):

self.cond.acquire()

self.cond.wait()

print self.name + ':Really, show me how much~\n'

self.cond.notify()

self.cond.wait()

print self.name +':you\'re so sweet~'

self.cond.notify()

self.cond.wait()

print self.name +':wow~~, that\'s '+L.pop()+'---the one I dreamed for so long, I love you'

self.cond.release()

if __name__ == '__main__':

cond = threading.Condition()

husband = boy(cond, 'Aidan')

wife = girl(cond,'PPP')

husband.start()

wife.start()

#husband.start()

husband.join() #wait untill these two threads end

wife.join()

print 'end converdarion\n'

本文标签: 多线程threadingPythoncondition