code: func (s *Scheduler) activeHostCount() int {
  	count := 0
  	for _, host := range s.hosts {
  		if !host.Shutdown {
  			count++
  		}
  	}
  	return count
  }
docs: // activeHostCount returns the number of active hosts (i.e. all hosts which
  // are not shutting down) and is used to determine how many omni jobs should
  // be running when calling formation.RectifyOmni