[go-nuts] dial io timeout and tcp short connection performance bottleneck

[刘桂祥]

>         I write a simple tcp server with golang
>         and use tcp short connect client to bench it.
>         when qps to 28K,  client have many dial io timeout
> 
>         I don't know what is the performance bottleneck??
>         
>         I modify the server:
>         cat /proc/sys/net/ipv4/tcp_max_syn_backlog    1024
>         cat cat /proc/sys/net/core/somaxconn          1024

        // tcpserver.go
        // a simple golang tcp server
        package main
        
        import (
        "io"
        "log"
        "net"
        )
        
        func init() {
        log.SetFlags(log.LstdFlags | log.Lshortfile)
        }
        func main() {
        tcpAddr, err := net.ResolveTCPAddr("tcp", ":9999")
        if err != nil {
        log.Println(err)
        return
        }   
        tcpListener, err := net.ListenTCP("tcp", tcpAddr)
        if err != nil {
        log.Println(err)
           return
        }   
        defer tcpListener.Close()
        
        for {
        tcpConn, err := tcpListener.AcceptTCP()
        if err != nil {
        log.Println(err)
        continue
        }
        go handle(tcpConn)
        }
        
        }
        // handle
        func handle(conn *net.TCPConn) {
        //log.Println(conn.RemoteAddr().String())
        
        buf := make([]byte, 1024)
        for {
        _, err := conn.Read(buf)
        if err != nil {
        if err != io.EOF {
        log.Println(err)
        }
        return
        }
        
        _, err = conn.Write([]byte{'h', 'e', 'l', 'l', 'o'})
        
        if err != nil {
        log.Println(err)
        }
        }
        }
    
    // tcpclient.go
    // tcp short connection bench
    package main
    
    import (
    "log"
    "net"
    "sync"
    "time"
    )
    
    var (
    wg sync.WaitGroup
    )
    
    func init() {
    log.SetFlags(log.LstdFlags | log.Lshortfile)
    }
    func main() {
    
    for i := 0; i < 150; i++ {
    wg.Add(1)
    go func() {
    for {
    req()
    time.Sleep(10 * time.Millisecond)
    }
    wg.Done()
    }()
    }
    wg.Wait()
    }
    // tcp req
    func req() {
    conn, err := net.DialTimeout("tcp", "192.168.67.133:9999", 
300*time.Millisecond)
    if err != nil {
    log.Println(err)
    return
    }
    // conn.SetDeadline(time.Now().Add(300 * time.Millisecond))
    defer conn.Close()
    _, err = conn.Write([]byte("client"))
    if err != nil {
    log.Println(err)
    return
    }
    buf := make([]byte, 1024)
    _, err = conn.Read(buf)
    if err != nil {
    log.Println(err)
    }
    }




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