Simple synchronisation block example in Go by using a WaitGroup

simple-sync.go

package main

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

func main() {
	// simple sync wait... queue work and wait for them all to finish
	wg := sync.WaitGroup{}
	for i := 0; i < 5; i++ {
		wg.Add(1) // note we add BEFORE starting the Goroutine
		go func(i int) {
			time.Sleep(time.Duration(rand.Intn(3)) * time.Second)
			fmt.Println(i)
			wg.Done()
		}(i)
	}
	wg.Wait()
	fmt.Println("done")
}