Parallelisation - Why does sleep pause only once?

Why do wait only the first goroutine with

func Sleep(d Duration)
http://golang.org/pkg/time
"Sleep pauses the current goroutine for the duration d."

but the rest is execute directly. I think cause the channel c chan string but i dont understand the behaviour between both.

My Example GoPlayground

All your go routines are running concurrently so they all sleep for 4 seconds at the same time, hence they all end at the same time.

You called them like this. The go means that all the getHostName functions run at once.

for i := 0; i < max; i++ {
	go getHostName(haveHost, ipadresse_3, i)
}

And this means that all the sleeps happen at the same time

func getHostName(h chan string, ipAdresse string, n int) {
	
	//Here!!!
	time.Sleep(4 * time.Second)
	ip := ipAdresse + strconv.Itoa(n)
	//ip, ok := net.LookupAddr(ip)
	if false {
		h <- ip + " - "
	} else {
		h <- "error" + strconv.Itoa(n)	
	}
}

So they all finish at the same time.