Go by Example: Timers

We often want to execute Go code at some point in the future, or repeatedly at some interval. Go’s built-in timer and ticker features make both of these tasks easy. We’ll look first at timers and then at tickers.

package main
import "time"
import "fmt"
func main() {

Timers represent a single event in the future. You tell the timer how long you want to wait, and it provides a channel that will be notified at that time. This timer will wait 2 seconds.

    timer1 := time.NewTimer(2 * time.Second)

The <-timer1.C blocks on the timer’s channel C until it sends a value indicating that the timer expired.

    fmt.Println("Timer 1 expired")

If you just wanted to wait, you could have used time.Sleep. One reason a timer may be useful is that you can cancel the timer before it expires. Here’s an example of that.

    timer2 := time.NewTimer(time.Second)
    go func() {
        fmt.Println("Timer 2 expired")
    stop2 := timer2.Stop()
    if stop2 {
        fmt.Println("Timer 2 stopped")

The first timer will expire ~2s after we start the program, but the second should be stopped before it has a chance to expire.

$ go run timers.go
Timer 1 expired
Timer 2 stopped

Next example: Tickers.