Example for sync.WaitGroup correct?

Question

Is this example usage of sync.WaitGroup correct? It gives the expected result, but I am unsure about the wg.Add(4) and the position of wg.Don

Answer 1

• small improvement based on Mroth answer
• using defer for Done is safer

  func dosomething(millisecs time.Duration, wg *sync.WaitGroup) {
  wg.Add(1)
  go func() {
      defer wg.Done()
      duration := millisecs * time.Millisecond
      time.Sleep(duration)
      fmt.Println("Function in background, duration:", duration)
  }()
}

func main() {
  var wg sync.WaitGroup
  dosomething(200, &wg)
  dosomething(400, &wg)
  dosomething(150, &wg)
  dosomething(600, &wg)
  wg.Wait()
  fmt.Println("Done")
}