Golang中的Ticker停止行为

huangapple
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英文:

Ticker Stop behaviour in Golang

问题

如果我正在遍历一个ticker通道并调用stop()，通道会停止但不会关闭。

在这个例子中：

  1. package main
  3. import (
  4.     "time"
  5.     "log"
  6. )
  8. func main() {
  9.     ticker := time.NewTicker(1 * time.Second)
  10.     go func(){
  11.         for _ = range ticker.C {
  12.             log.Println("tick")
  13.         }
  14.         log.Println("stopped")
  15.     }()
  16.     time.Sleep(3 * time.Second)
  17.     log.Println("stopping ticker")
  18.     ticker.Stop()
  19.     time.Sleep(3 * time.Second)
  20. }

运行结果为：

  1. 2013/07/22 14:26:53 tick
  2. 2013/07/22 14:26:54 tick
  3. 2013/07/22 14:26:55 tick
  4. 2013/07/22 14:26:55 stopping ticker

因此，该goroutine永远不会退出。有没有更好的处理这种情况的方法？我应该关心该goroutine永远不会退出吗？

英文:

If I am ranging over a ticker channel and call stop() the channel is stopped but not closed.

In this Example:

  1. package main
  3. import (
  4.     "time"
  5.     "log"
  6. )
  8. func main() {
  9.     ticker := time.NewTicker(1 * time.Second)
  10.     go func(){
  11.         for _ = range ticker.C {
  12.             log.Println("tick")
  13.         }
  14.         log.Println("stopped")
  15.     }()
  16.     time.Sleep(3 * time.Second)
  17.     log.Println("stopping ticker")
  18.     ticker.Stop()
  19.     time.Sleep(3 * time.Second)
  20. }

Running produces:

  1. 2013/07/22 14:26:53 tick
  2. 2013/07/22 14:26:54 tick
  3. 2013/07/22 14:26:55 tick
  4. 2013/07/22 14:26:55 stopping ticker

So that goroutine never exits. Is there a better way to handle this case? Should I care that the goroutine never exited?

答案1

得分: 23

使用了第二个通道如Volker建议的。这是我最终运行的代码：

  1. package main
  3. import (
  4.     "log"
  5.     "time"
  6. )
  8. // 每个滴答运行一次函数
  9. // 从函数中返回false以停止滴答器
  10. func Every(duration time.Duration, work func(time.Time) bool) chan bool {
  11.     ticker := time.NewTicker(duration)
  12.     stop := make(chan bool, 1)
  14.     go func() {
  15.         defer log.Println("滴答器停止")
  16.         for {
  17.             select {
  18.             case time := <-ticker.C:
  19.                 if !work(time) {
  20.                     stop <- true
  21.                 }
  22.             case <-stop:
  23.                 return
  24.             }
  25.         }
  26.     }()
  28.     return stop
  29. }
  31. func main() {
  32.     stop := Every(1*time.Second, func(time.Time) bool {
  33.         log.Println("滴答")
  34.         return true
  35.     })
  37.     time.Sleep(3 * time.Second)
  38.     log.Println("停止滴答器")
  39.     stop <- true
  40.     time.Sleep(3 * time.Second)
  41. }
英文:

Used a second channel as Volker suggested. This is what I ended up running with:

  1. package main
  3. import (
  4.     &quot;log&quot;
  5.     &quot;time&quot;
  6. )
  8. // Run the function every tick
  9. // Return false from the func to stop the ticker
  10. func Every(duration time.Duration, work func(time.Time) bool) chan bool {
  11.     ticker := time.NewTicker(duration)
  12.     stop := make(chan bool, 1)
  14.     go func() {
  15.         defer log.Println(&quot;ticker stopped&quot;)
  16.         for {
  17.             select {
  18.             case time := &lt;-ticker.C:
  19.                 if !work(time) {
  20.                     stop &lt;- true
  21.                 }
  22.             case &lt;-stop:
  23.                 return
  24.             }
  25.         }
  26.     }()
  28.     return stop
  29. }
  31. func main() {
  32.     stop := Every(1*time.Second, func(time.Time) bool {
  33.         log.Println(&quot;tick&quot;)
  34.         return true
  35.     })
  37.     time.Sleep(3 * time.Second)
  38.     log.Println(&quot;stopping ticker&quot;)
  39.     stop &lt;- true
  40.     time.Sleep(3 * time.Second)
  41. }

答案2

得分: 15

在你的goroutine中，在ticker和done通道之间选择，并在第二个通道上发送信号“done”。

根据你真正想要做什么，可能存在更好的解决方案，但从简化的演示代码中很难判断。

英文:

Signal "done" on a second channel and select in your goroutine between ticker and done channel.

Depending on what you really want to do a better solution might exist, but this is hard to tell from the reduced demo code.

答案3

得分: 8

你可以这样做。

  1. package main
  3. import (
  4.     "fmt"
  5.     "time"
  6. )
  8. func startTicker(f func()) chan bool {
  9.     done := make(chan bool, 1)
  10.     go func() {
  11.         ticker := time.NewTicker(time.Second * 1)
  12.         defer ticker.Stop()
  13.         for {
  14.             select {
  15.             case <-ticker.C:
  16.                 f()
  17.             case <-done:
  18.                 fmt.Println("done")
  19.                 return
  20.             }
  21.         }
  22.     }()
  23.     return done
  24. }
  26. func main() {
  27.     done := startTicker(func() {
  28.         fmt.Println("tick...")
  29.     })
  30.     time.Sleep(5 * time.Second)
  31.     close(done)
  32.     time.Sleep(5 * time.Second)
  33. }
英文:

you can do like this.

  1. package main
  3. import (
  4.     &quot;fmt&quot;
  5.     &quot;time&quot;
  6. )
  8. func startTicker(f func()) chan bool {
  9.     done := make(chan bool, 1)
  10.     go func() {
  11.         ticker := time.NewTicker(time.Second * 1)
  12.         defer ticker.Stop()
  13.         for {
  14.             select {
  15.             case &lt;-ticker.C:
  16.                 f()
  17.             case &lt;-done:
  18.                 fmt.Println(&quot;done&quot;)
  19.                 return
  20.             }
  21.         }
  22.     }()
  23.     return done
  24. }
  26. func main() {
  27.     done := startTicker(func() {
  28.         fmt.Println(&quot;tick...&quot;)
  29.     })
  30.     time.Sleep(5 * time.Second)
  31.     close(done)
  32.     time.Sleep(5 * time.Second)
  33. }

答案4

得分: 0

如果你需要节省更多的空间，可以使用空结构体(struct{})的通道，它不占用内存。正如上面提到的，不要在其中发送任何东西，只需关闭通道，实际上发送的是零值。

英文:

If you need to save more space, use channels of empty structs (struct{}) which costs no memory. And as mentioned above, don't send something in it - just close, which actually sends zero value.

答案5

得分: 0

我认为这是一个很好的答案

  1. func doWork(interval time.Duration, work func(), stop chan struct{}, done func()) {
  2. 	t := time.NewTicker(interval)
  3. 	for {
  4. 		select {
  5. 		case <-t.C:
  6. 			work()
  7. 		case _, more := <-stop:
  8. 			if !more {
  9. 				done()
  10. 			}
  11. 			return
  12. 		}
  13. 	}
  14. }
  16. func Test_workTicker(t *testing.T) {
  18. 	var wg sync.WaitGroup
  19. 	wg.Add(1)
  20. 	stop := make(chan struct{})
  22. 	go doWork(
  23. 		500*time.Millisecond,
  24. 		func() { fmt.Println("做工作") },
  25. 		stop,
  26. 		func() {
  27. 			fmt.Println("在go协程中完成")
  28. 			wg.Done()
  29. 		},
  30. 	)
  32. 	time.Sleep(5 * time.Second)
  33. 	close(stop)
  34. 	wg.Wait()
  35. 	fmt.Println("在主函数中完成")
  36. }
英文:

I think this is a nice answer

  1. func doWork(interval time.Duration, work func(), stop chan struct{}, done func()) {
  2. 	t := time.NewTicker(interval)
  3. 	for {
  4. 		select {
  5. 		case &lt;-t.C:
  6. 			work()
  7. 		case _, more := &lt;-stop:
  8. 			if !more {
  9. 				done()
  10. 			}
  11. 			return
  12. 		}
  13. 	}
  14. }
  16. func Test_workTicker(t *testing.T) {
  18. 	var wg sync.WaitGroup
  19. 	wg.Add(1)
  20. 	stop := make(chan struct{})
  22. 	go doWork(
  23. 		500*time.Millisecond,
  24. 		func() { fmt.Println(&quot;do work&quot;) },
  25. 		stop,
  26. 		func() {
  27. 			fmt.Println(&quot;done in go routine&quot;)
  28. 			wg.Done()
  29. 		},
  30. 	)
  32. 	time.Sleep(5 * time.Second)
  33. 	close(stop)
  34. 	wg.Wait()
  35. 	fmt.Println(&quot;done in main&quot;)
  36. }

huangapple
  • 本文由 发表于 2013年7月23日 05:28:53
  • 转载请务必保留本文链接：https://go.coder-hub.com/17797754.html
  • go
  • ticker
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