golang concurrency

producer_consumer.go

package main

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

func main() {
	tasks := []string{"task1", "task2", "task3", "task4", "task5", "task6"}
	ch := make(chan string, 3)
	var wg sync.WaitGroup

	go worker(&wg, ch)
	go worker(&wg, ch)
	go worker(&wg, ch)
	go worker(&wg, ch)
	go worker(&wg, ch)
	go worker(&wg, ch)

	for _, task := range tasks {
		wg.Add(1)
		ch <- task
	}
	close(ch)

	wg.Wait()
}

func worker(wg *sync.WaitGroup, ch chan string) {
	for t := range ch {
		process(t)
		wg.Done()
	}
}

func process(s string) {
	fmt.Printf("start processing %s\n", s)
	time.Sleep(time.Duration(rand.Intn(3)) * time.Second)
	fmt.Printf("done processing %s\n", s)
}