why does tcp-keep-alive affect the tcp-close in go?

Question

I have a server, when accepting a connection, I set tcp-keep-alive for 120seconds.But when I close the connection, acctually the connection doesn't close.by netstat -anp | grep 9999, I found the state was ESTABLISHED .And the client didn't receive any error from the socket , either. I want to know will tcp-keep-alive affect the tcp-close?

PS go 1.4 centos

package main
import (
    "github.com/felixge/tcpkeepalive"
    "net"
    "runtime"
    "time"
)
func  Start() {
    tcpAddr, err := net.ResolveTCPAddr("tcp4", "127.0.0.1:9999")
    if err != nil {
        return
    }
    listener, err := net.ListenTCP("tcp", tcpAddr)
    if err != nil {
        return
    }
    for {
        conn, err := listener.AcceptTCP()
        if err != nil {
            continue
        }
        go handleClient(conn)
    }
}

func handleClient(conn *net.TCPConn) {
    kaConn, err := tcpkeepalive.EnableKeepAlive(conn)
    if err != nil {
    } else {
        kaConn.SetKeepAliveIdle(120 * time.Second)
        kaConn.SetKeepAliveCount(4)
        kaConn.SetKeepAliveInterval(5 * time.Second)
    }
    time.Sleep(time.Second * 3)
    conn.Close()
    return
}

func main() {
    runtime.GOMAXPROCS(runtime.NumCPU())
    Start()
}

Answer 1

Don't use that keepalive library. It duplicates file descriptors, and fails to close them.

If you need to set KeepAlive, use the methods provided in the net package.

• SetKeepAlive
• SetKeepAlivePeriod

You likely don't need any extra options set, but only if you're certain you do, then you can try to apply what's needed with the appropriate syscalls.