proc_master.go
func (mp *master) fetchLoop() {
	min := mp.Config.MinFetchInterval
	time.Sleep(min)
	for {
		t0 := time.Now()
		mp.fetch()
		//duration fetch of fetch
		diff := time.Now().Sub(t0)
		if diff < min {
			delay := min - diff
			//ensures at least MinFetchInterval delay.
			//should be throttled by the fetcher!
			time.Sleep(delay)
		}
	}
}
func (mp *master) fetchLoop() {
	min := mp.Config.MinFetchInterval
	time.Sleep(min)
	for {
		t0 := time.Now()
		mp.fetch()
		//duration fetch of fetch
		diff := time.Now().Sub(t0)
		if diff < min {
			delay := min - diff
			//ensures at least MinFetchInterval delay.
			//should be throttled by the fetcher!
			time.Sleep(delay)
		}
	}
}
//fetchLoop is run in a goroutine