加锁

https://www.bilibili.com/video/BV1jJ411c7s3?p=120

互斥锁

var  mutex sync.Mutex // 创建锁头

mutex.Lock()  //上锁

mutex.Unlock  // 取消锁

同步等待组

var wg sync.WaitGroup

wg.Add()
wg.Done()

wg.Wait()

读写锁

var  mutex sync.RWMutex