goroutine leak with buffered channel in Go

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英文:

goroutine leak with buffered channel in Go

问题

以下是《The Go Programming Language》中的代码:

func mirroredQuery() string {
    responses := make(chan string, 3)
    go func() { responses <- request("asia.gopl.io") }()
    go func() { responses <- request("europe.gopl.io") }()
    go func() { responses <- request("americas.gopl.io") }()
    return <-responses // 返回最快的响应
}

func request(hostname string) (response string) { /* ... */ }

书中说:

如果我们使用了一个无缓冲的通道,那么两个较慢的 goroutine 将会在试图发送它们的响应到一个没有其他 goroutine 会接收的通道上而被阻塞。这种情况被称为 goroutine 泄漏,它是一个 bug。与垃圾变量不同,泄漏的 goroutine 不会自动回收,因此当不再需要时,确保 goroutine 自行终止非常重要。

问题是为什么这种情况会导致 goroutine 泄漏。在我看来,有缓冲的通道的容量是 3,3 个 goroutine 会发送它们的请求并立即退出,这不会导致泄漏。

英文:

Th following codes is in The Go Programming Language

func mirroredQuery() string {
    responses := make(chan string, 3)
    go func() { responses &lt;- request(&quot;asia.gopl.io&quot;) }()
    go func() { responses &lt;- request(&quot;europe.gopl.io&quot;) }()
    go func() { responses &lt;- request(&quot;americas.gopl.io&quot;) }()
    return &lt;-responses // return the quickest response
}

func request(hostname string) (response string) { /* ... */ }

And book says
> Had we used an unbuffered channel, the two slower
> goroutines would have gotten stuck trying to send their responses
> on a channel from which no goroutine will ever receive . This situation, called a goroutine leak, would be a bug . Unlike garbage
> variables, leaked goroutines are not automatically collec ted, so
> it is important to make sure that goroutines terminate themselves
> when no longer needed.

<br/>
And the question is why this situation will cause a goroutine leak.In my idea, the buffered channel's cap is 3, and 3 goroutines will send their requests and exit immediately which will not cause the leak.

答案1

得分: 4

代码显示的部分不会导致泄漏。

正如段落所述:

> 如果我们使用一个非缓冲通道

意思是:如果我们使用了非缓冲通道...

所以只有当通道是非缓冲的时候,泄漏才会发生。

英文:

The code shown does not cause a leak.

As the paragraph states:

> Had we used an unbuffered channel

Meaning: if we had used an unbuffered channel...

So only if the channel was unbuffered the leak would occur.

huangapple
  • 本文由 发表于 2017年9月10日 21:43:21
  • 转载请务必保留本文链接:https://go.coder-hub.com/46141353.html
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