Shows how to use a wait group to make sure all the go routines are done.

waitgroup.go

package main

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

func main() {
	var tasks = []int{5, 2, 7, 4, 2, 9, 8}
	var wg sync.WaitGroup
	maind := random(100, 3000)
	for _, v := range tasks {
		go func(c int) {
			wg.Add(1)
			defer allDone(c)
			d := random(500, 3000)
			time.Sleep(time.Duration(d) * time.Millisecond)
			fmt.Printf("%d + 1 = %d\n", c, c+1)
			wg.Done()
		}(v)
	}
	time.Sleep(time.Duration(maind) * time.Millisecond)
	fmt.Println("Main process done.")
	wg.Wait()
	fmt.Println("All tasks complete!")
}

func allDone(c int) {
	fmt.Println("All done with", c)
}

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