golang x/time/rate example

main.go

package main

import (
	"fmt"
	"sync"
	"time"

	"golang.org/x/time/rate"
)

func main() {
	// 800 requests per minute. 
	l := rate.NewLimiter(rate.Every(time.Second/13), 1) 
	wg := &sync.WaitGroup{}
	for i := 0; i < 100; i++ {
		wg.Add(1)
		go run(l, wg, i)
	}
	wg.Wait()
	fmt.Printf("Completed the requests\n")
}

func run(l *rate.Limiter, wg *sync.WaitGroup, i int) {

	r := l.Reserve()
	wait := r.Delay()

	if wait > time.Second*3 {
		fmt.Printf("%d: Wait Too Long For Request %s\n", i, wait.String())
	} else {
		time.Sleep(wait)
		fmt.Printf("%d: Waited For Request. %s\n", i, wait.String())
	}

	wg.Done()
}