Go 语言中Select与for结合使用时可能会遇到的坑

最新推荐文章于 2025-04-30 11:01:20 发布

Dev-L

最新推荐文章于 2025-04-30 11:01:20 发布

阅读量2k

点赞数

CC 4.0 BY-SA版权

分类专栏： go

本文链接：https://blog.youkuaiyun.com/u010525694/article/details/91320144

go 专栏收录该内容

27 篇文章

订阅专栏

本文探讨了在Go语言中，当`for`循环与`select`结合使用时可能导致死循环的问题。文章提供了两种解决方案，推荐使用带有标签的`break`语句来跳出循环，或者使用`goto`语句进行控制流程的跳转，以避免无限循环的发生。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

问题现象

当for 和 select结合使用时，break语言是无法跳出for之外的：

package main

import (
	"fmt"
	"time"
	"context"
)
func main(){
	d := time.Now().Add(3000 * time.Millisecond)
	ctx, cancel := context.WithDeadline(context.Background(), d)

	// Even though ctx will be expired, it is good practice to call its
	// cancelation function in any case. Failure to do so may keep the
	// context and its parent alive longer than necessary.
	defer cancel()

	for{
		select {
		case <-time.After(1 * time.Second):
			fmt.Println("overslept")
		case <-ctx.Done():
			fmt.Println(ctx.Err())
			break 
		}
	}
	println("Done!")

}

上面的程序会造成死循环！

解决方案1：使用label(推荐)

package main

import (
	"fmt"
	"time"
	"context"
)
func main(){
	d := time.Now().Add(3000 * time.Millisecond)
	ctx, cancel := context.WithDeadline(context.Background(), d)

	// Even though ctx will be expired, it is good practice to call its
	// cancelation function in any case. Failure to do so may keep the
	// context and its parent alive longer than necessary.
	defer cancel()
	DONE:
	for{
		select {
		case <-time.After(1 * time.Second):
			fmt.Println("overslept")
		case <-ctx.Done():
			fmt.Println(ctx.Err())
			break DONE
		}
	}
	println("Done!")

}

解决方案2：使用goto

package main

import (
	"fmt"
	"time"
	"context"
)
func main(){
	d := time.Now().Add(3000 * time.Millisecond)
	ctx, cancel := context.WithDeadline(context.Background(), d)

	// Even though ctx will be expired, it is good practice to call its
	// cancelation function in any case. Failure to do so may keep the
	// context and its parent alive longer than necessary.
	defer cancel()

	for{
		select {
		case <-time.After(1 * time.Second):
			fmt.Println("overslept")
		case <-ctx.Done():
			fmt.Println(ctx.Err())
			goto DONE
		}
	}
	DONE:println("Done!")

}