code: func (s *Serf) getQueueMax() int {
  	max := s.config.MaxQueueDepth
  	if s.config.MinQueueDepth > 0 {
  		s.memberLock.RLock()
  		max = 2 * len(s.members)
  		s.memberLock.RUnlock()
  
  		if max < s.config.MinQueueDepth {
  			max = s.config.MinQueueDepth
  		}
  	}
  	return max
  }
docs: // getQueueMax will get the maximum queue depth, which might be dynamic depending
  // on how Serf is configured.