如何开启

func say(name string) {
    fmt.Println("hello, I'm",name)
    time.Sleep(time.Second)
}
func main() {
    //如何开启线程
    go say("rui")
    say("z")
}

如何让主线程等待goroutines

var wg sync.WaitGroup
func say(name string) {
    fmt.Println("hello, I'm",name)
    time.Sleep(time.Second*5)
    wg.Done()
}
func main() {
    wg.Add(2)//等待2个任务完成
    go say("rui")
    go say("z")
    wg.Wait()//等待其他goroutines完成
    fmt.Println("exit")
}

模拟打球

var wg sync.WaitGroup
func play(name string ,ch chan int) {
    defer wg.Done()//写在前面
    for true {
        ball,ok:=<-ch
        if !ok{//通道关闭
            fmt.Printf("%s win!\n",name)
            return//结束方法
        }
        source := rand.NewSource(time.Now().UnixNano())
        r := rand.New(source)
        n := r.Intn(100)
        if n%10==0 {//把球打飞
            close(ch)
            fmt.Printf("%s lose the ball\n",name)
            return
        }
        ball++
        fmt.Printf("%s receive the ball %dtimes \n",name,ball)
        ch<-ball
    }
}
func main() {
    ch := make(chan int, 0)
    wg.Add(2)//等待2个任务完成
    go play("one",ch)
    go play("two",ch)
    ch<-0//线程启动后才能启用channel，不然没有人接收
    wg.Wait()//等待其他goroutines完成
    fmt.Println("exit")
}

Race Condition的三种解决方案

var counter int32
var wait sync.WaitGroup
func UnsafeIntCounter() {
    defer wait.Done()
    for i := 0; i < 10000; i++ {
        counter++
    }
}
func main() {
    wait.Add(2)
    go UnsafeIntCounter()
    go UnsafeIntCounter()
    wait.Wait()
    fmt.Println(counter)
}
//10237

1. sync.Mutex ```go //全局 var mtx sync.Mutex

//函数中 mtx.Lock() counter++ mtx.Unlock()

2. atomic
```go
func AtomicIntCounter() {
    defer wait.Done()
    for i := 0; i < 10000; i++ {
        atomic.AddInt32(&counter,1)
    }
}

3.