net/http: Server.Close does defer Lock

[peter-mogensen]

Please answer these questions before submitting your issue. Thanks!

What version of Go are you using (go version)?

Go master HEAD 8d0c105

What operating system and processor architecture are you using (go env)?

GOARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH=""
GORACE=""
GOROOT="/usr/lib/go"
GOTOOLDIR="/usr/lib/go/pkg/tool/linux_amd64"
GO15VENDOREXPERIMENT="1"
CC="gcc"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0"
CXX="g++"
CGO_ENABLED="1"

What did you do?

package main

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

type server3 struct {
	http.Server
}

func (s *server3) Serve(l net.Listener) error {
	fmt.Println("Serving")
	time.Sleep(time.Second)
	return s.Server.Serve(l)
}

// naming is a bitch
func (s *server3) Shutdown() {
	fmt.Println("Closing")
	s.Close()
}

func main() {

	srv := &server3{}
	srvEnd :=  make(chan error)


	for {
		l, err := net.Listen("tcp","")
		if err != nil {
			log.Fatal(err)
		}
		
		go func() {
			err := srv.Serve(l)
			srvEnd <- err 
		}()

		time.Sleep(time.Second)
		
		srv.Shutdown()

		fmt.Println("Close done")
		
		err = <- srvEnd
		
		fmt.Println(err)
	}
}

What did you expect to see?

Serving
Closing
Close done
^C

What did you see instead?

Serving
Closing
^C

[peter-mogensen]

$ git diff
diff --git a/src/net/http/server.go b/src/net/http/server.go
index 0959ac6..d78fd71 100644
--- a/src/net/http/server.go
+++ b/src/net/http/server.go
@@ -2362,7 +2362,7 @@ func (s *Server) closeDoneChanLocked() {
 // regardless of their state. For a graceful shutdown, use Shutdown.
 func (s *Server) Close() error {
        s.mu.Lock()
-       defer s.mu.Lock()
+       defer s.mu.Unlock()
        s.closeDoneChanLocked()
        err := s.closeListenersLocked()
        for c := range s.activeConn {

[bradfitz]

That's a very wordy bug report. Thanks to @peter-mogensen for summarizing.

[gopherbot]

CL https://golang.org/cl/33026 mentions this issue.