Question

var mu sync.RWMutex

//goroutine 1
go func() {
    mu.Lock()
    defer mu.Unlock()
   //something else
}()
//goroutine 2
go func() {
    mu.Lock()
    defer mu.Unlock()
    //something else
}()
//goroutine 3
go func() {
    mu.RLock()
    defer mu.RUnlock()
    //something else
}()
//goroutine 4
go func() {
    mu.RLock()
    defer mu.RUnlock()
    //something else
}()

goroutine 1现在获得锁定，goroutine 2,3,4被阻止。当goroutine 1释放锁定时，goroutine会先被唤醒吗？随机？

Answer 1

为了确保锁定最终可供作者使用，被阻止的Lock调用会阻止新读者获取锁定。如果在Lock上goroutine 3之前goroutine 2在RLock上阻塞，则goroutine 2将在goroutine 3之前运行。如果goroutine 3在goroutine 2阻塞之前在RLock上阻塞，则执行顺序未指定Lock。

当一个阻止goroutine的RWMutex解锁时会被唤醒

1 个答案: