Odd behavior: continues to serve content after listener.Close()

[AlasdairF]

Hello,

I'm attempting to do a graceful shutdown by closing the listener. However, it doesn't work; I can continue to request new pages and they continue to be served, even after s.Serve returns, until the entire application ends.

    package main

    import (
        "github.com/valyala/fasthttp"
        "fmt"
        "log"
        "net"
        "time"
    )

    var listener net.Listener

    func root(ctx *fasthttp.RequestCtx) {
        if string(ctx.Path()) == `/close` {
            fmt.Fprint(ctx, "CLOSE\n")
            err := listener.Close()
            if err != nil {
                log.Println(err)
            }
        }
        fmt.Fprintf(ctx, "Hi there! RequestURI is %q", ctx.RequestURI())
    }

    func main() {
        var err error
        listener, err = net.Listen(`tcp`, `:8081`)
        if err != nil {
            log.Fatal(err)
        }
        s := &fasthttp.Server{
            Handler: root,
        }
        err = s.Serve(listener)
        if err != nil {
            log.Println(err)
        }
        log.Println(`Exiting in 30 seconds`)
        time.Sleep(time.Second * 30)
        log.Println(`Exiting`)
    }

[valyala]

Server.Serve returns when listener is closed, so new connections aren't accepted. But the client (web browser) still holds old keep-alive connection, which is served by fasthttp regardless of the original listener state until the connection is closed.

BTW, net/http.Server does the same thing. Try it:

package main

import (
        "fmt"
        "log"
        "net"
        "net/http"
        "time"
)

var listener net.Listener

func root(w http.ResponseWriter, r *http.Request) {
        if r.URL.Path == `/close` {
                fmt.Fprint(w, "CLOSE\n")
                err := listener.Close()
                if err != nil {
                        log.Println(err)
                }
        }
        fmt.Fprintf(w, "Hi there! RequestURI is %q", r.RequestURI)
}

func main() {
        var err error
        listener, err = net.Listen(`tcp`, `:8081`)
        if err != nil {
                log.Fatal(err)
        }
        s := &http.Server{
                Handler: http.HandlerFunc(root),
        }
        err = s.Serve(listener)
        if err != nil {
                log.Println(err)
        }
        log.Println(`Exiting in 30 seconds`)
        time.Sleep(time.Second * 30)
        log.Println(`Exiting`)
}