Why won't time.Sleep work in time.Tick?, instead waits 10 seconds

i have the code:

	n := time.Now()
	i := 0
	for range time.Tick(5 * time.Second) {
		fmt.Printf("start %d %s \n ", i, time.Since(n))
		time.Sleep(10)
		fmt.Printf("end %d %s \n", i, time.Since(n))
		i++
	}

output:

start 0 5.001125s 
 end 0 5.001386916s 
start 1 10.001112041s 
 end 1 10.001232416s 
start 2 15.001064s 
 end 2 15.001094958s 

Trigger every 5 seconds, program execution takes 10 seconds, I found that the sleep method does not take effect, every 5 seconds will automatically print end, no wait 10 seconds.

question:

1. What is the reason for this?

2. I need to wait until the execution of the program in each loop is complete before I start recalculating the 5 seconds. What do I do?

> What is the reason for this?

time.Sleep takes a parameter of type time.Duration which under the covers is an int64 representing nanoseconds.

As a result, this sleeps for 10 nanoseconds:

time.Sleep(10)

To sleep for 10 seconds, use one of the predefined consts:

time.Sleep(10*time.Second)

> I need to wait until the execution of the program in each loop is complete before I start recalculating the 5 seconds

If you want to wait at least 5s between each loop iteration - then don't use a Ticker. A ticker will loop on a regular interval. Some examples:

• if a loop task takes 2s, then the next loop iteration will begin in 3s (5 minus 2)
• if the task takes 8s (missing a tick), then there will be zero wait between iterations;
• if the task takes 12s (missing 2 ticks) - again there will be zero wait

So if you want to ensure a consistent pause between iterations, put a sleep at the end of the loop.