使用goroutine，模拟4个售票口出售火车票的案例。4个售票口同时卖票

package main

import (
	"fmt"
	"math/rand"
	"sync"
	"time"
)

var ticket =10


var mutex sync.Mutex //创建锁头

var wg sync.WaitGroup //同步等待组对象

func main(){
	/*
	 4个售票口
	*/
	wg.Add(4)
	go saleTickets("售票窗口1")
	go saleTickets("售票窗口2")
	go saleTickets("售票窗口3")
	go saleTickets("售票窗口4")
	wg.Wait()
	fmt.Println("售票结束")
}

func saleTickets(name string){
   rand.Seed(time.Now().UnixNano())
   defer  wg.Done()
   for {
   	//上锁
   	mutex.Lock()
   	if ticket >0 {
   		time.Sleep(time.Duration(rand.Intn(1000))*time.Microsecond)
   		fmt.Println(name,"售出:",ticket)
   		ticket--
	}else{
      mutex.Unlock()//条件不满足解锁
      fmt.Println(name,"售罄,没有票了……")
      break
	}
	mutex.Unlock()
   }
}