timer

// 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](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(time.Second * 2)

    // The `<-timer1.C` blocks on the timer's channel `C`
    // until it sends a value indicating that the timer
    // expired.
    <-timer1.C
    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() {
        <-timer2.C
        fmt.Println("Timer 2 expired")
    }()
    
    //如果想要看到timer2的执行结果，可以让main函数sleep一会等待goroutine执行结束
    //time.Sleep(time.Second * 2)
    
    stop2 := timer2.Stop()
    if stop2 {
        fmt.Println("Timer 2 stopped")
    }
}

//输出
Timer 1 expired
Timer 2 stopped

ticker

// [Timers](timers) are for when you want to do
// something once in the future - _tickers_ are for when
// you want to do something repeatedly at regular
// intervals. Here's an example of a ticker that ticks
// periodically until we stop it.

package main

import "time"
import "fmt"

func main() {

    // Tickers use a similar mechanism to timers: a
    // channel that is sent values. Here we'll use the
    // `range` builtin on the channel to iterate over
    // the values as they arrive every 500ms.
    ticker := time.NewTicker(time.Millisecond * 500)
    go func() {
        for t := range ticker.C {
            fmt.Println("Tick at", t)
        }
    }()

    // Tickers can be stopped like timers. Once a ticker
    // is stopped it won't receive any more values on its
    // channel. We'll stop ours after 1600ms.
    time.Sleep(time.Millisecond * 1600)
    ticker.Stop()
    fmt.Println("Ticker stopped")
}

//输出
Tick at 2009-11-10 23:00:00.5 +0000 UTC m=+0.500000000
Tick at 2009-11-10 23:00:01 +0000 UTC m=+1.000000000
Tick at 2009-11-10 23:00:01.5 +0000 UTC m=+1.500000000
Ticker stopped

参考文章：

• timer

• ticker