net/http: request.Body.Close() can be called after RoundTrip() returns

[soslanco]

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

$ go version
go version go1.20 linux/amd64

Does this issue reproduce with the latest release?

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

go env Output

$ go env
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/root/.cache/go-build"
GOENV="/root/.config/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/usr/local/godev/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/usr/local/godev"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/go"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
GOVCS=""
GOVERSION="go1.20"
GCCGO="gccgo"
GOAMD64="v1"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/usr/local/godev/src/bench/go.mod"
GOWORK=""
CGO_CFLAGS="-O2 -g"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-O2 -g"
CGO_FFLAGS="-O2 -g"
CGO_LDFLAGS="-O2 -g"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -Wl,--no-gc-sections -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build159046709=/tmp/go-build -gno-record-gcc-switches"
GOROOT/bin/go version: go version go1.20 linux/amd64
GOROOT/bin/go tool compile -V: compile version go1.20
uname -sr: Linux 5.14.0-162.12.1.el9_1.x86_64
/lib64/libc.so.6: GNU C Library (GNU libc) stable release version 2.34.
gdb --version: GNU gdb (GDB) Red Hat Enterprise Linux 10.2-10.el9

What did you do?

rd := &bytes.Reader{}
body := make([]byte, 1048576)
for i := 0; i < 1000; i++ {
	rd.Reset(body)
	_, err := http.Post("http://127.0.0.1:8080", "application/octet-stream", rd)
	if err != nil {
		log.Fatalf("[%d] %v", i, err)
	}
}

What did you expect to see?

reusing without errors

What did you see instead?

2023/02/14 14:52:48 [7] Post "http://127.0.0.1:12345": net/http: HTTP/1.x transport connection broken: http: ContentLength=1048576 with Body length 1015808

[seankhliao]

what's your full test code?
transport connection broken doesn't point to an error with the post contents

[soslanco]

It's full code from main function. In another hand just web server handling post requests on 8080 port.

package main

import (
	"bytes"
	"log"
	"net/http"
)

func main() {
	rd := &bytes.Reader{}
	body := make([]byte, 1048576)
	for i := 0; i < 1000; i++ {
		rd.Reset(body)
		_, err := http.Post("http://127.0.0.1:8080", "application/octet-stream", rd)
		if err != nil {
			log.Fatalf("[%d] %v", i, err)
		}
	}
}

[seankhliao]

That's not enough to reproduce the issue, it may be that your server is breaking the connection

[soslanco]

You may run for example nginx and test previous code:
docker run --rm -p 8080:80 nginx

or use something like that

package main

import (
	"io"
	"log"
	"net/http"
)

func main() {
	helloHandler := func(w http.ResponseWriter, req *http.Request) {
		io.WriteString(w, "Hello, world!\n")
	}
	http.HandleFunc("/", helloHandler)
	log.Fatal(http.ListenAndServe(":8080", nil))
}

But if we allocate variables for every request then code works fine:

for i := 0; i < 1000; i++ {
	body := make([]byte, 1048576)
	rd := bytes.NewReader(body)
	_, err := http.Post("http://127.0.0.1:8080", "application/octet-stream", rd)
	if err != nil {
		log.Fatalf("[%d] %v", i, err)
	}
}

[seankhliao]

Duplicate of #51907