Go routine to load http endpoint with different ua string

load.go

package main

import (
	"fmt"
	"net/http"
	"os"
	"strconv"
	"sync"
	"sync/atomic"
)

func startLoadTest(count int, url string) {
	var wg sync.WaitGroup
	var finishedCount uint64

	for i := 0; i < count; i++ {
		client := &http.Client{
			CheckRedirect: func(req *http.Request, via []*http.Request) error {
				return http.ErrUseLastResponse
			},
		}
		wg.Add(1)
		go func() {
			req, _ := http.NewRequest("GET", url, nil)
			req.Header.Set("User-Agent", "ua_" + strconv.FormatUint(finishedCount, 10))
			resp, err := client.Do(req)
			if err != nil {
				fmt.Println(fmt.Sprintf("Got error: %v, status: %v", err, resp))
				return
			}
			defer func() {
				if resp != nil && resp.Body != nil {
					resp.Body.Close()
				}
				wg.Done()
			}()
			atomic.AddUint64(&finishedCount, 1)
			fmt.Println(fmt.Sprintf("Finished GET request #%v, status: %d", finishedCount, resp.StatusCode))
		}()
	}
	wg.Wait()
	fmt.Println("Done!")
}

func main() {
	count, err := strconv.Atoi(os.Args[1])
	if err != nil {
		panic("error in cmd line arg: 1, should be int")
	}
	url := os.Args[2]
	startLoadTest(count, url)
}