Maybe your client's local ports is used out. threre are only about 65000
ports you can use to make a connection from a client to server per IP. You
can check output of netstat to confirm that.
On Sunday, June 11, 2017 at 9:48:30 AM UTC+8, 刘桂祥 wrote:
>
> //question
> > I write a simple golang tcp server
> > and use tcp short connect client to bench it.
> > when qps up to 28K, client have many dial i/o 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 /proc/sys/net/core/somaxconn 1024
>
> //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)
> }
>
> }
> 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)
> }
> }
> }
>
> // 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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