code: def start(self, join=False):
          
          Thread.start(self)
  
          if join:
              try:
                  while self.is_alive():
                      self.join(timeout=60)
                  self.logger.info("worker {0} exit unexpected, try to shutdown it".format(self.option.consumer_name))
                  self.shutdown()
              except KeyboardInterrupt:
                  self.logger.info("*** try to exit **** ")
                  self.shutdown()
docs: when calling with join=True, must call it in main thread, or else, the Keyboard Interrupt won't be caputured.
          :param join: default False, if hold on until the worker is stopped by Ctrl+C or other reasons.
          :return: