main.go

package main

import (
	"fmt"
	"math/rand"
	"sync"
	"sync/atomic"
	"time"

	"github.com/korovkin/limiter"
)

func main() {

	var total int64

	nTask := 100
	nRoutine := 10
	ch := make(chan int)
	var wg sync.WaitGroup
	wg.Add(1)

	go func() {
		for i := 0; i < nTask; i++ {
			ch <- i
		}
		wg.Done()
	}()

	limit := limiter.NewConcurrencyLimiter(nRoutine)
	for i := 0; i < nTask; i++ {
		limit.Execute(func() {
			// do some work
			x := <-ch

			result := fungsiBodoh(x)
			fmt.Println(result)

			atomic.AddInt64(&total, int64(result))

			time.Sleep(time.Second * 2)
		})
	}
	limit.Wait()

	fmt.Println(total)
}

func fungsiBodoh(x int) int {
	time.Sleep(time.Duration(random(500, 4500)) * time.Millisecond)
	return x * x
}

func random(min, max int) int {
	rand.Seed(time.Now().Unix())
	return rand.Intn(max-min) + min
}