remove sent to channel

tcp.go

@@ -430,13 +430,12 @@ func (h *tcpServer) gracefulStop() {
 	done := make(chan struct{})
 	go func() {
 		h.opts.Wait.Wait()
-		done <- struct{}{}
+		close(done)
 	}()
 
 	select {
 	case <-tm.C:
 	case <-done:
-		close(done)
 	}
 }