package main

import (
  "fmt"
  "sync"
)

func main() {
  N:=4
  waitGroup := sync.WaitGroup{}
  waitGroup.Add(N)

  //
  //for i:=0;i<N ;i++  {
  //  fmt.Println("*************")
  //  waitGroup.Done()
  //}

  for i:=0;i<N ;i++  {
    go func() {
      fmt.Println("-------")
      waitGroup.Done()
    }()
  }
  waitGroup.Wait()
}

WaitGroup是同步等待的包