Go并发最佳实践

1、使用goroutines管理服务状态

type Server strung { quit chan bool }
func NewServer() *Server{
    s := &Server{make(chan bool)}    go s.run()    return s
}func (s *Server) run() {    for {        select {            case: <- s.quit:
                fmt.Println("finishing task")
                time.Sleep(time.Secod)
                fmt.Println("task done")
                s.quit <- true
                return
             case: <- time.After(time.Secod)
                 fmt.Println("running task")
        }
    }
}

func (s *Server) Stop() {
    fmt.Println("server stoppint")
    <- s.quit
    fmt.Println("server stopped")
}

func main() {
    s := NewServer()
    time.Sleep(2 * time.Second)
    s.Stop  //会阻塞等待quit通知}

2、使用buffer channel避免goroutine泄漏

首先我们来开发一个应用程序实现广播功能：

• 实现一个向其他服务发送消息的函数。

func sendMsg(msg, addr string) error {
    conn, err := net.Dial("tcp", addr)       if err != nil {        return err
    }    defer conn.Close()
    _, err = fmt.Fprint(conn, msg)   return err
}

• 广播功能
  向多个服务发送同一条消息：

func broadcastMsg(msg string, addrs []string) error {
    err := make(chan error)    for _, add := range addrs {        go func (adds string) {
            err <- sendMsg(msg, addr)
            fmt.Println("done")
        }(adds)
    }    for _ = range addrs {        if err := <- err; err != nil {            return err
        }
    }    return nil}

func main() {
    addr := []string{"localhost:8080, "http://google.com"}
    err := broadcastMsg("hi", addr)
    time.Sleep(time.Second)    if err != nil {
        fmt.Println(err)        return
    }
    fmt.Println("消息发送成功")
}

• 写channel会被阻塞
• goroutine保存对chan的引用
• chan无法被垃圾回收

使用带缓冲带channel

func broadcasMsg(msg string, adds []string) error {
    errc := make(chan error, len(addrs))    for _, addr := range addrs {        go func(addr string) {
            errc <- sendMsg(msg, addr)
            fmt.Println("done")
        }(addr)
    }    for _ = range addrs {        if err := <-errc; err != nil {            return err
        }
    }    return nil}

使用quit通道

func broadcastMsg(msg string, addrs []string) error {
    errc := make(chan error)
    quit := make(chan struct)    
    defer close(quit)    
    for _, addr := range addrs {        go func(addr string) {            select {                case errc <- sendMsg(msg, addr):
                    fmt.Println("done")                case <-  quit:
                    fmt.Println("quit")
            }
        }(addr)
    }    for _ = range addrs {        if err := <- errc; err != nil {            return err
        }
    }    return nil}