package main import ( "fmt" "sync" ) var wg sync.WaitGroup // 1 func routine(i int) { defer wg.Done() // 3 fmt.Printf("routine %v finished\n", i) } func main() { wg.Add(10) // 2 for i := 0; i < 10; i++ { go routine(i) // * } wg.Wait() // 4 fmt.Println("main finished") }