#!/usr/bin/env python# -*- coding: utf-8 -*-import threading import timeimport randomsemaphore = threading.Semaphore(0)def consumer():    print("consumer is waiting.")    semaphore.acquire()    print("Consumer notify: consumed item number %s." % item)def producer():    global item    time.sleep(10)    item = random.randint(1, 1000)    print("producer nofity: produced item number %s." % item)    semaphore.release()  if __name__ == "__main__":    for i in range(0, 5):        t1 = threading.Thread(target=producer)        t2 = threading.Thread(target=consumer)        t1.start()        t2.start()        t1.join()        t2.join()    print("program teminated.")