time: document that Tick interval gap can exceed duration #30271
Description
What version of Go are you using (go version)?
go version go1.11.5 windows/amd64
What did you do?
The documentation example for time.Tick ( https://golang.org/pkg/time/#Tick ) states that the channel returns now. But if the routine inside the tick exceeds the duration, the ticker produces a one-time gap. This may need clarification in the documentation example. You may check this playground example: https://play.golang.org/p/ImIhZTLYciq
package main
import (
"fmt"
"time"
)
func main() {
c := time.Tick(1 * time.Second)
for now := range c {
fmt.Printf("now\t\t%v\n", now)
fmt.Printf("time.Now()\t%v\n", time.Now())
time.Sleep(3 * time.Second)
}
}
What did you expect to see?
time.Now() should be the same as now.
What did you see instead?
It produces a gap in the second interval:
now 2009-11-10 23:00:01 +0000 UTC m=+1.000000001
time.Now() 2009-11-10 23:00:01 +0000 UTC m=+1.000000001
now 2009-11-10 23:00:02 +0000 UTC m=+2.000000001
time.Now() 2009-11-10 23:00:04 +0000 UTC m=+4.000000001 <==== +2s
now 2009-11-10 23:00:05 +0000 UTC m=+5.000000001
time.Now() 2009-11-10 23:00:07 +0000 UTC m=+7.000000001
now 2009-11-10 23:00:08 +0000 UTC m=+8.000000001
time.Now() 2009-11-10 23:00:10 +0000 UTC m=+10.000000001
now 2009-11-10 23:00:11 +0000 UTC m=+11.000000001
time.Now() 2009-11-10 23:00:13 +0000 UTC m=+13.000000001