func main() { var wg sync.WaitGroup sem := make(chan struct{}, 2) // 最多允许2个并发同时执行 taskNum := 10 for i := 0; i < taskNum; i++ { wg.Add(1) go func(id int) { defer wg.Done() sem <- struct{}{} // 获取信号 defer func() { <-sem }() // 释放信号 // do something for task time.Sleep(time.Second * 2) fmt.Println(id, time.Now()) }(i) } wg.Wait() }