信号量

import threading,time
def run(n):
    semaphore.acquire()
    time.sleep(1)
    print(‘run the thread:%s\n‘ % n)
    semaphore.release()

if __name__ ==‘__main__‘:
    semaphore = threading.BoundedSemaphore(5)#信号量
    for i in range(20):
        t = threading.Thread(target = run,args=(i,))
        t.start()
while threading.active_count() != 1:
    pass
else:
    print(‘---all threads done‘)

信号量

原文：http://www.cnblogs.com/zhangjixiang/p/7770877.html