Go Channel和Go协程与指针变量，所有的goroutine都处于休眠状态-死锁。

huangapple
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英文:

Go Channel and go routine with pointer variables all goroutines are asleep - deadlock

问题

我花了整个晚上来解决这个错误，但是没有成功。当我运行程序时，出现了以下错误："所有的goroutine都处于休眠状态 - 死锁！"。我理解这是因为主程序在例程有机会执行任务之前就退出了，我原以为使用sync.WaitGroup会有所帮助，但实际上并没有解决问题。

我想设置一定数量的例程，并使用通道发送URL以检查HTTP状态码。我想限制对网站的并发调用数量。我已经按照使用字符串而不是结构体的示例进行了操作，它是有效的。

非常感谢任何帮助！

  1. package main
  3. import (
  4. 	"fmt"
  5. 	"sync"
  6. 	"time"
  7. )
  9. const (
  10. 	numPollers = 2 // 要启动的Poller goroutine数量
  11. )
  13. var urls = []string{
  14. 	"http://www.google.com/",
  15. 	"http://golang.org/",
  16. 	"http://blog.golang.org/",
  17. 	"http://golangtutorials.blogspot.fr",
  18. 	"https://gobyexample.com/",
  19. }
  21. // Resource 表示此程序要轮询的HTTP URL。
  22. type Resource struct {
  23. 	url string
  24. }
  26. func Poller(in <-chan *Resource, wg *sync.WaitGroup) {
  27. 	//defer wg.Done()
  28. 	for r := range in {
  29. 		fmt.Printf("Finished: %v - %v\n", r.url, time.Now())
  30. 	}
  31. 	wg.Done()
  32. }
  34. func main() {
  35. 	var wg sync.WaitGroup
  36. 	pending := make(chan *Resource)
  38. 	wg.Add(len(urls))
  40. 	go Poller(pending, &wg)
  42. 	go func() {
  43. 		for _, url := range urls {
  44. 			wg.Add(1)
  45. 			fmt.Println("SENT > Pending url " + url)
  46. 			pending <- &Resource{url: url}
  47. 		}
  48. 	}()
  50. 	wg.Wait()
  52. 	fmt.Printf("Finished all goroutines: %v\n", time.Now())
  53. }

链接：https://play.golang.org/p/B-HSiDo2Qg

英文:

I spend my evening looking at how to fix this error but I haven't succeeded. When I run the program I have the following error : "all goroutines are asleep - deadlock!". I understand this is because the main program is exited before the routine has the possibility to do its tasks and I thought using sync.WaitGroup would help but not really :/

I want to set a number of routine and use channels to send urls in order to check http status code. I want to limit the number of concurrency call to a website. I've followed examples doing the same thing with string instead of struct and it worked.

Any help would be well appreciated Go Channel和Go协程与指针变量，所有的goroutine都处于休眠状态-死锁。

  1. package main
  3. import (
  4. 	&quot;fmt&quot;
  5. 	&quot;sync&quot;
  6. 	&quot;time&quot;
  7. )
  9. const (
  10. 	numPollers = 2                // number of Poller goroutines to launch
  11. )
  13. var urls = []string{
  14. 	&quot;http://www.google.com/&quot;,
  15. 	&quot;http://golang.org/&quot;,
  16. 	&quot;http://blog.golang.org/&quot;,
  17. 	&quot;http://golangtutorials.blogspot.fr&quot;,
  18. 	&quot;https://gobyexample.com/&quot;,
  19. }
  21. // Resource represents an HTTP URL to be polled by this program.
  22. type Resource struct {
  23. 	url      string
  24. }
  26. func Poller(in &lt;-chan *Resource, wg *sync.WaitGroup) {
  27. 	//defer wg.Done()
  28. 	for r := range in {
  29. 		fmt.Printf(&quot;Finished: %v - %v\n&quot;, r.url, time.Now())
  30. 	}
  31. 	wg.Done()
  32. }
  34. func main() {
  35. 	var wg sync.WaitGroup
  36. 	pending := make(chan *Resource)
  38. 	wg.Add(len(urls))
  40. 	go Poller(pending, &amp;wg)
  42. 	go func() {
  43. 		for _, url := range urls {
  44. 			wg.Add(1)
  45. 			fmt.Println(&quot;SENT &gt; Pending url &quot; + url)
  46. 			pending &lt;- &amp;Resource{url: url}
  47. 		}
  48. 	}()
  50. 	wg.Wait()
  52. 	fmt.Printf(&quot;Finished all goroutines: %v\n&quot;, time.Now())
  53. }

https://play.golang.org/p/B-HSiDo2Qg

答案1

得分: 3

首先，你对wg.Add()的调用次数太多了。你为每个运行的goroutine调用了一次。请参考http://golang.org/pkg/sync/#WaitGroup。其次，在写入完成后，你没有关闭通道。这是你代码的修改版本：

  1. package main
  3. import (
  4.     "fmt"
  5.     "sync"
  6.     "time"
  7. )
  9. const (
  10.     numPollers = 2 // 要启动的Poller goroutine的数量
  11. )
  13. var urls = []string{
  14.     "http://www.google.com/",
  15.     "http://golang.org/",
  16.     "http://blog.golang.org/",
  17.     "http://golangtutorials.blogspot.fr",
  18.     "https://gobyexample.com/",
  19. }
  21. // Resource 表示此程序要轮询的HTTP URL。
  22. type Resource struct {
  23.     url string
  24. }
  26. func Poller(in <-chan *Resource, wg *sync.WaitGroup) {
  27.     defer wg.Done()
  28.     for r := range in {
  29.         fmt.Printf("Finished: %v - %v\n", r.url, time.Now())
  30.     }
  31. }
  33. func main() {
  34.     var wg sync.WaitGroup
  35.     pending := make(chan *Resource)
  37.     wg.Add(numPollers)
  39.     go Poller(pending, &wg)
  41.     go func() {
  42.         defer close(pending)
  43.         defer wg.Done()
  44.         for _, url := range urls {
  45.             fmt.Println("SENT > Pending url " + url)
  46.             pending <- &Resource{url: url}
  47.         }
  48.     }()
  50.     wg.Wait()
  52.     fmt.Printf("Finished all goroutines: %v\n", time.Now())
  53. }

和 https://play.golang.org/p/ucUlZEZMZM

英文:

First, you have too many calls to wg.Add(). You call that once for each goroutine you're running. See http://golang.org/pkg/sync/#WaitGroup. Second, you didn't close the channel after you were done writing to it. Here's a modified version of your code:

  1. package main
  3. import (
  4.     &quot;fmt&quot;
  5.     &quot;sync&quot;
  6.     &quot;time&quot;
  7. )
  9. const (
  10.     numPollers = 2                // number of Poller goroutines to launch
  11. )
  13. var urls = []string{
  14.     &quot;http://www.google.com/&quot;,
  15.     &quot;http://golang.org/&quot;,
  16.     &quot;http://blog.golang.org/&quot;,
  17.     &quot;http://golangtutorials.blogspot.fr&quot;,
  18.     &quot;https://gobyexample.com/&quot;,
  19. }
  21. // Resource represents an HTTP URL to be polled by this program.
  22. type Resource struct {
  23.     url      string
  24. }
  26. func Poller(in &lt;-chan *Resource, wg *sync.WaitGroup) {
  27.     defer wg.Done()
  28.     for r := range in {
  29.         fmt.Printf(&quot;Finished: %v - %v\n&quot;, r.url, time.Now())
  30.     }
  31. }
  33. func main() {
  34.     var wg sync.WaitGroup
  35.     pending := make(chan *Resource)
  37.     wg.Add(2)
  39.     go Poller(pending, &amp;wg)
  41.     go func() {
  42.         defer close(pending)
  43.         defer wg.Done()
  44.         for _, url := range urls {
  45.             fmt.Println(&quot;SENT &gt; Pending url &quot; + url)
  46.             pending &lt;- &amp;Resource{url: url}
  47.         }
  48.     }()
  50.     wg.Wait()
  52.     fmt.Printf(&quot;Finished all goroutines: %v\n&quot;, time.Now())
  53. }

and https://play.golang.org/p/ucUlZEZMZM

答案2

得分: 1

你忘记关闭通道，并且你的等待组时间太长。这个链接对我有用：https://play.golang.org/p/yasIzaCbmQ

英文:

You forget to close channel, and your wait group is too long. This works for me: https://play.golang.org/p/yasIzaCbmQ

huangapple
  • 本文由 发表于 2014年12月16日 07:12:14
  • 转载请务必保留本文链接：https://go.coder-hub.com/27494857.html
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