使用channel同步

package mainimport (    "fmt")func printNumber(num int, c chan struct{}) {  fmt.Println(num)  c <- struct{}{}}func main() {  sign := make(chan struct{}, 10)  for i:=0;i<10;i++ {    go printNumber(i, sign)  }  for i:=0;i<10;i++{    <-sign  }  fmt.Println("Done.")}

使用sync.WaitGroup

package mainimport (    "fmt"    "sync")func printNumber(num int, callback func()) {  fmt.Println(num)  callback()}func main() {  var wg sync.WaitGroup  wg.Add(10)  for i:=0;i<10;i++ {    go printNumber(i, wg.Done)  }  wg.Wait()  fmt.Println("Done.")}