text: import threading
  import time
  
  exitFlag = 0
  
  class myThread (threading.Thread):
      def __init__(self, threadID, name, counter):
          threading.Thread.__init__(self)
          self.threadID = threadID
          self.name = name
          self.counter = counter
      def run(self):
          print ("开始线程：" + self.name)
          print_time(self.name, self.counter, 3)
          print ("退出线程：" + self.name)
  
  def print_time(threadName, delay, counter):
      while counter:
          if exitFlag:
              threadName.exit()
          time.sleep(delay)
          print ("%s: %s" % (threadName, time.ctime(time.time())))
          counter -= 1
  
  # 创建新线程
  thread1 = myThread(1, "Thread-1", 1)
  thread2 = myThread(2, "Thread-2", 2)
  
  # 开启新线程
  thread1.start()
  thread2.start()
  thread1.join()
  thread2.join()
  print ("退出主线程")