Golang使用WaitGroup控制子任务完成

sync

var wg sync.WaitGroup

for i := 0; i < 5; i++ {
    wg.Add(1)
    go func(id int) {
        defer wg.Done()
        // 执行任务
        fmt.Printf("任务 %d 完成\n", id)
    }(i)
}

wg.Wait() // 等待所有任务完成
fmt.Println("所有子任务已完成")

package main

import (
    "fmt"
    "net/http"
    "sync"
)

func fetch(url string, wg *sync.WaitGroup) {
    defer wg.Done()

    resp, err := http.Get(url)
    if err != nil {
        fmt.Printf("请求失败 %s: %v\n", url, err)
        return
    }
    defer resp.Body.Close()

    fmt.Printf("成功获取 %s，状态码: %d\n", url, resp.StatusCode)
}

func main() {
    urls := []string{
        "https://httpbin.org/get",
        "https://httpbin.org/delay/2",
        "https://httpbin.org/status/200",
    }

    var wg sync.WaitGroup

    for _, url := range urls {
        wg.Add(1)
        go fetch(url, &wg)
    }

    wg.Wait()
    fmt.Println("所有HTTP请求完成")
}

go func() {
    wg.Add(1) // 错误：Add在goroutine内
    defer wg.Done()
}()

ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
defer cancel()

// 启动任务...
wg.Wait() // 仍需等待，但受上下文约束