Go_Context

package main

import (
	"fmt"
	"sync"
	"time"
)

// 为什么需要context？
var wg sync.WaitGroup
var notify bool

func f() {
	defer wg.Done()
	for {
		fmt.Println("==")
		time.Sleep(time.Millisecond * 500)
		if notify {
			break
		}
	}
}

func main() {
	wg.Add(1)
	go f()
	time.Sleep(time.Second * 5)
	// 如何通知子goroutine退出
	notify = true
	wg.Wait()

}

package main

import (
	"fmt"
	"sync"
	"time"
)

// 为什么需要context？
var wg sync.WaitGroup
var exitChan = make(chan bool, 1)

func f() {
	defer wg.Done()
FORLOOP:
	for {
		fmt.Println("周琳")
		time.Sleep(time.Millisecond * 500)
		select {
		case <-exitChan:
			break FORLOOP
		default:
		}
	}
}

func main() {

	wg.Add(1)
	go f()
	time.Sleep(time.Second * 5)
	// 如何通知子goroutine退出
	exitChan <- true
	wg.Wait()
}