package main

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

type Sth struct {
	x    int64
	wg   sync.WaitGroup
	lock sync.Mutex
}

func (s *Sth) add() {
	for i := 0; i < 10000; i++ {
		s.lock.Lock()
		s.x++
		s.lock.Unlock()
	}
	s.wg.Done()
}

func main() {
	var s Sth
	s.wg.Add(2)
	go s.add()
	go s.add()
	s.wg.Wait()
	fmt.Println(s)

	time.Sleep(time.Second)
	fmt.Println("xiaowei zhaodandan")
}