try reproduce resty race

main.go

package main

import (
	"crypto/tls"
	"fmt"
	"log"
	"net/http"
	"sync"
	"sync/atomic"
	"time"

	resty "gopkg.in/resty.v1"
)

func serverErrorRetryCondition(r *resty.Response) (bool, error) {
	retryStatuses := [...]int{
		http.StatusInternalServerError,
		http.StatusBadGateway,
		http.StatusServiceUnavailable,
		http.StatusGatewayTimeout}
	respStatus := r.StatusCode()
	for _, status := range retryStatuses {
		if status == respStatus {
			return true, nil
		}
	}
	return false, nil
}

func main() {
	client := resty.New().SetHostURL("http://localhost:9988")
	client.SetRetryCount(3).SetRetryMaxWaitTime(time.Minute).AddRetryCondition(serverErrorRetryCondition)
	client.SetTLSClientConfig(&tls.Config{InsecureSkipVerify: true})
	go server()
	wg := &sync.WaitGroup{}
	numRoutines := 10
	wg.Add(numRoutines)
	for i := 0; i < numRoutines; i++ {
		go executer(client, wg)
	}
	wg.Wait()
}

func server() {
	http.HandleFunc("/", func(writer http.ResponseWriter, request *http.Request) {
		writer.WriteHeader(500)
		request.Write(writer)
	})
	var srv http.Server
	srv.Addr = ":9988"
	log.Fatal(srv.ListenAndServe())
}

const msg = "abcdefghijklmnopqrstuvwxyz1234567890abcdefghijklmnopqrstuvwxyz1234567890abcdefghijklmnopqrstuvwxyz1234567890abcdefghijklmnopqrstuvwxyz1234567890abcdefghijklmnopqrstuvwxyz1234567890abcdefghijklmnopqrstuvwxyz1234567890abcdefghijklmnopqrstuvwxyz1234567890abcdefghijklmnopqrstuvwxyz1234567890abcdefghijklmnopqrstuvwxyz1234567890abcdefghijklmnopqrstuvwxyz1234567890abcdefghijklmnopqrstuvwxyz1234567890abcdefghijklmnopqrstuvwxyz1234567890abcdefghijklmnopqrstuvwxyz1234567890abcdefghijklmnopqrstuvwxyz1234567890abcdefghijklmnopqrstuvwxyz1234567890v"

var count int32

func executer(client *resty.Client, wg *sync.WaitGroup) {
	for i := 0; i < 100; i++ {
		req := client.NewRequest().SetHeader("x-header", msg)
		req.SetBody([]byte(msg))
		_, err := req.Execute("POST", "/")
		cnt := atomic.AddInt32(&count, 1)
		fmt.Printf("Executing: %d\n", cnt)
		if err != nil {
			panic(err)
		}
	}
	wg.Done()
}