1 import threading,time 2  3 def  run(n): 4     semaphore.acquire() 5     time.sleep(1) 6     print("run in the %s thread"%n) 7     semaphore.release() 8  9 if __name__ ==  '__main__':10     semaphore = threading.BoundedSemaphore(5)#最多允许5个线程同时执行11     for i in range(22):12         t = threading.Thread(target=run,args=(i,))13         t.start()14 15 while threading.active_count() != 1:16     pass# print("active count :",threading.active_count())17 18 else:19     print("all threads done")