Data race when running DoTimeout(...)

[Lallassu]

I get a data race from time to time and the below code triggers it. Am I missing something in my DoRequest function to make this race-safe?

The data race (go run -race .): race.log

Code used to trigger it (localhost:80 is just an nginx responding 200 OK with a small body):

package main

import (
	"crypto/tls"
	"fmt"
	"time"

	"github.com/valyala/fasthttp"
	"github.com/valyala/fasthttp/fasthttpproxy"
)

func main() {
        to := time.Second * 2
	go func() {
		for {
			DoRequest(false, "GET", "http://localhost", to)
		}
	}()
	go func() {
		for {
			DoRequest(false, "GET", "http://localhost", to)
		}
	}()
	time.Sleep(60 * time.Second)
}

func DoRequest(verifyTLS bool, method, url string, timeout time.Duration) ([]byte, int, int64, error) {
	req := fasthttp.AcquireRequest()
	resp := fasthttp.AcquireResponse()
	defer fasthttp.ReleaseRequest(req)
	defer fasthttp.ReleaseResponse(resp)

	req.Header.Set("Connection", "close")
	req.Header.SetMethod(method)
	req.SetRequestURI(url)

	client := &fasthttp.Client{
		DialDualStack: true,
		ReadTimeout:   timeout,
		TLSConfig:     &tls.Config{InsecureSkipVerify: !verifyTLS},
		Dial:          fasthttpproxy.FasthttpProxyHTTPDialer(),
	}

	tReqStart := time.Now()

	var body []byte
	err := client.DoTimeout(req, resp, timeout)
	// ReleaseRequest(resp) will re-use underlying data structure so we need a copy here.
	body = append(body, resp.Body()...)

	if err != nil {
		fmt.Printf("failed: %s\n", err.Error())
		return body, resp.StatusCode(), time.Since(tReqStart).Microseconds(), err
	}

	return body, resp.StatusCode(), time.Since(tReqStart).Microseconds(), nil
}

Edit: Using fasthttp 1.31 and Go 1.16.3.

[erikdubbelboer]

You're right. It seems this pull request, #1106, introduced a race condition. I have fixed it here: 6d4db9b
We'll probably do a new release next week when #1135 is fixed and merged.