go - 如果我们无法从传递给该例程的 channel 收听，如何停止 goroutine

Question

我遇到了一个关于 goroutines 的问题。假设有一个 channel ，我们通过来自 main 的 goroutine 传递这个 channel 。现在，如果我们无法从 main 收听此 channel (以防在收听之前发生返回/ panic )。 goroutine 不会停止。如何在出错时停止这个 goroutine？

在多次调用goroutine中的函数的情况下，routine的数量不断增加。

package main

import (
    "fmt"
    "runtime"
)

func test(a chan string) {
    defer func() {
        close(a)
        fmt.Println("channel close")
    }()
    fmt.Println("sending to channel")
    a <- "1"
    fmt.Println("sent to channel")
}

func method() string {

    fmt.Println("method starting no. of routine=>",
        runtime.NumGoroutine())
    b := make(chan string)

    go test(b)
    fmt.Println("method current no. of routine=>",
        runtime.NumGoroutine())

    return "error" //if this is executed the routines keeps on
    //increasing
    a := <-b
    return a
}

func main() {
    defer fmt.Println("final main no. of routine=>",
        runtime.NumGoroutine())
    i := 0
    //firing 10 request for method
    for {
        if i < 10 {
               fmt.Println(method())
               i++
        } else {
               break
        }

    }
}

输出:

method starting no. of routine=> 1

method current no. of routine=> 2

error

method starting no. of routine=> 2

method current no. of routine=> 3

error

method starting no. of routine=> 3

method current no. of routine=> 4

error

.....就这样一直增加

Answer 1

例程可以根据上下文停止。在使用上下文之前，您应该知道只有带循环的例程才需要停止控制，那些死例程不需要停止。

上下文示例:

func main(){
    ctx, cancel := context.WithCancel(context.Background())
    go func(c context.Context){
        for {
            select{
                case <-c.Done():
                   fmt.Println("exit success")
                default:
                   // service
                   fmt.Println("my logic service loop")
            }    
        }
    }(ctx)
    time.Sleep(5 * time.Second)
   cancel()
}