net/http: ReverseProxy always trigger http.Server.ReadTimeout

[L-P]

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

go version go1.7.4 linux/amd64

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

GOARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/lpeltier/Documents/go"
GORACE=""
GOROOT="/opt/go"
GOTOOLDIR="/opt/go/pkg/tool/linux_amd64"
CC="gcc"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build343847435=/tmp/go-build -gno-record-gcc-switches"
CXX="g++"
CGO_ENABLED="1"

What did you do?

I have a http.ReverseProxy as the handler of a http.Server
configured with a ReadTimeout, and serving a large file.

package main

import (
	"net/http"
	"net/http/httputil"
	"net/url"
	"time"
)

func main() {
	server := &http.Server{
		Addr:        ":1990",
		ReadTimeout: 1 * time.Second,
		Handler:     newProxy(),
	}
	server.ListenAndServe()
}

func newProxy() *httputil.ReverseProxy {
	director := func(req *http.Request) {
		req.URL, _ = url.Parse("http://releases.ubuntu.com/16.04/ubuntu-16.04.1-desktop-amd64.iso")
		req.Host = req.URL.Host
	}

	return &httputil.ReverseProxy{
		Director: director,
	}
}

What did you expect to see?

I expect the proxy to serve the whole file.

What did you see instead?

The ReadTimeout always trigger and closes the connection even though
the full request has been read and the response is being sent to the client.

$ curl localhost:1990 > /dev/null
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0 1443M    0  9.7M    0     0   9.7M      0  0:02:27  0:00:01  0:02:26  9.7M
curl: (18) transfer closed with 1503043678 bytes remaining to read

Time Spent equals my ReadTimeout.

[ALTree]

I can't reproduce the problem on go1.8.

I believe this is a dup of #18447, which was fixed on tip by ecac827.

[L-P]

Can't reproduce on go version go1.8rc2 linux/amd64 either. Thanks.