Hi Darkofday:
I doubt that if the client's local port is used out, it should't
return dail io timeout
I use one client with less worker it don't have dial timeout and
when another client with the same worker count to bench the server, now
two clients have dial io timeout
so I guess the performance bottleneck is in the server
在 2017年6月12日星期一 UTC+8上午8:54:20，Darkofday Darkofday写道：
>
> 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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