package main

import (
    "sync"
    "fmt"
    "time"
)

func main()  {
    var wg sync.WaitGroup

    ch := make(chan int)

    goroutineNum := 2

    for i := 0; i < goroutineNum; i ++ {
        wg.Add(1)
        go doSomeThing(i, ch, &wg)
    }

    for j := 0; j < goroutineNum; j ++  {
        ch<-j
    }

    close(ch)

    wg.Wait()

    fmt.Printf("all is done\n")
}

func doSomeThing(goroutineId int, ch chan int, wg *sync.WaitGroup)  {
    defer wg.Done()

    for {
        select {
        case _ = <-ch:
            time.Sleep(2 * time.Second)
            fmt.Printf("%v is done\n", goroutineId)
            return
        }
    }
}