A simple script that can hammer a given URL with configurable concurrency and number of requests.

simple-load-test.go

package main

import (
	"flag"
	"io"
	"io/ioutil"
	"log"
	"net"
	"net/http"
	"sync"
	"sync/atomic"
	"time"
)

func hammer(url string, reqCount *int64, wg *sync.WaitGroup) {
	defer wg.Done()

	req, err := http.NewRequest("GET", url, nil)
	if err != nil {
		log.Fatal(err)
	}
	transport := &http.Transport{
		DialContext: (&net.Dialer{
			Timeout:   30 * time.Second,
			KeepAlive: 30 * time.Second,
		}).DialContext,
		MaxIdleConns:          500,
		IdleConnTimeout:       90 * time.Second,
		ExpectContinueTimeout: 1 * time.Second,
	}
	client := http.Client{Transport: transport}

	for {
		remaining := atomic.AddInt64(reqCount, -1)
		if remaining < 0 {
			return
		}

		resp, err := client.Do(req)
		if err != nil {
			log.Println(err)
			continue
		}

		if _, err := io.Copy(ioutil.Discard, resp.Body); err != nil {
			log.Println(err)
		}
		if err := resp.Body.Close(); err != nil {
			log.Println(err)
		}
	}
}

func main() {
	totalRequests := flag.Int64("reqs", 1000000, "number of requests")
	vus := flag.Int("vus", 200, "the number of pseudo-VUs")
	testURL := flag.String("url", "http://127.0.0.1/", "the url you want to hammer")
	flag.Parse()

	wg := &sync.WaitGroup{}
	remainingReqs := *totalRequests
	start := time.Now()
	for i := 0; i < *vus; i++ {
		wg.Add(1)
		go hammer(*testURL, &remainingReqs, wg)
	}
	go func() {
		for {
			reqs := atomic.LoadInt64(&remainingReqs)
			if reqs < 0 {
				return
			}
			log.Printf("Remaining requests: %d", reqs)
			time.Sleep(1 * time.Second)
		}
	}()
	wg.Wait()
	elapsedTime := time.Now().Sub(start)
	reqsPerSecond := float64(*totalRequests) * float64(time.Second) / float64(elapsedTime)
	log.Printf("Requests per second: %.02f", reqsPerSecond)
}