Load test HTTP server with 'golang.org/x/time/rate' rate limiter

main.go

package main

/*
Run via `go run main.go`
Test via `curl -i localhost:4000`

Load test via https://github.com/rakyll/hey
hey -n 500000 -c 50 -q 166 -m GET http://localhost:4000

Summary:
  Total:	61.0789 secs
  Slowest:	0.0740 secs
  Fastest:	0.0000 secs
  Average:	0.0010 secs
  Requests/sec:	8186.1292

  Total data:	6000000 bytes
  Size/request:	12 bytes

Response time histogram:
  0.000 [1]	|
  0.007 [498465]	|■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■
  0.015 [1096]	|
  0.022 [213]	|
  0.030 [183]	|
  0.037 [39]	|
  0.044 [1]	|
  0.052 [0]	|
  0.059 [1]	|
  0.067 [0]	|
  0.074 [1]	|


Latency distribution:
  10% in 0.0003 secs
  25% in 0.0005 secs
  50% in 0.0008 secs
  75% in 0.0013 secs
  90% in 0.0019 secs
  95% in 0.0025 secs
  99% in 0.0042 secs

Details (average, fastest, slowest):
  DNS+dialup:	0.0000 secs, 0.0000 secs, 0.0740 secs
  DNS-lookup:	0.0000 secs, 0.0000 secs, 0.0105 secs
  req write:	0.0000 secs, 0.0000 secs, 0.0329 secs
  resp wait:	0.0009 secs, 0.0000 secs, 0.0349 secs
  resp read:	0.0000 secs, 0.0000 secs, 0.0315 secs

Status code distribution:
  [200]	500000 responses

 */

import (
	"fmt"
	"net/http"
	"golang.org/x/time/rate"
	"log"
)
// Max 8400 requests per second with a burst of 8500
var limiter = rate.NewLimiter(8400, 8500)

func main () {

	mux := http.NewServeMux()
	mux.HandleFunc("/", helloHandler)

	log.Print("Listening on :4000...")
	http.ListenAndServe(":4000", limitMiddleware(mux))
}

func limitMiddleware(next http.Handler) http.Handler {
    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        if limiter.Allow() == false {
            http.Error(w, http.StatusText(429), http.StatusTooManyRequests)
            return
        }

        next.ServeHTTP(w, r)
    })
}

func helloHandler(w http.ResponseWriter, r *http.Request) {
	fmt.Fprintf(w, "Hello World!")
}