fix review

Author: lyuxuan

Diff for: examples/features/debugging/README.md

@@ -1,16 +1,18 @@
 # Debugging
 
+Currently, grpc provides two major tools to help user debug issues, which are logging and channelz.
+
+## Logs
 gRPC has put substantial logging instruments on critical paths of gRPC to help users debug issues. 
 The [Log Levels](https://github.com/grpc/grpc-go/blob/master/Documentation/log_levels.md) doc describes
 what each log level means in the gRPC context.
 
-We also provides a runtime debugging tool, Channelz, to help users with live debugging.
-
-## Logs
 To turn on the logs for debugging, run the code with the following environment variable: 
 `GRPC_GO_LOG_VERBOSITY_LEVEL=99 GRPC_GO_LOG_SEVERITY_LEVEL=info`. 
 
 ## Channelz
+We also provides a runtime debugging tool, Channelz, to help users with live debugging.
+
 See the channelz blog post here ([link](https://grpc.io/blog/a_short_introduction_to_channelz)) for
 details about how to use channelz service to debug live program.
 

Diff for: examples/features/debugging/client/main.go

@@ -16,13 +16,13 @@
  *
  */
 
+// Binary client is an example client.
 package main
 
 import (
 	"log"
 	"net"
 	"os"
-	"os/signal"
 	"time"
 
 	"golang.org/x/net/context"
@@ -39,10 +39,11 @@ const (
 
 func main() {
 	/***** Set up the server serving channelz service. *****/
-	lis, err := net.Listen("tcp", ":50050")
+	lis, err := net.Listen("tcp", ":50052")
 	if err != nil {
 		log.Fatalf("failed to listen: %v", err)
 	}
+	defer lis.Close()
 	s := grpc.NewServer()
 	service.RegisterChannelzServiceToServer(s)
 	go s.Serve(lis)
@@ -81,11 +82,8 @@ func main() {
 		}
 	}
 
-	/***** Wait for CTRL+C to exit *****/
-	// Unless you exit the program with CTRL+C, channelz data will be available for querying.
+	/***** Wait for user exiting the program *****/
+	// Unless you exit the program (e.g. CTRL+C), channelz data will be available for querying.
 	// Users can take time to examine and learn about the info provided by channelz.
-	ch := make(chan os.Signal, 1)
-	signal.Notify(ch, os.Interrupt)
-	// Block until a signal is received.
-	<-ch
+	select {}
 }

Diff for: examples/features/debugging/server/main.go

@@ -16,13 +16,12 @@
  *
  */
 
+// Binary server is an example server.
 package main
 
 import (
 	"log"
 	"net"
-	"os"
-	"os/signal"
 	"time"
 
 	"golang.org/x/net/context"
@@ -67,16 +66,13 @@ func main() {
 	defer s.Stop()
 
 	/***** Start three GreeterServers(with one of them to be the slowServer). *****/
-	var listeners []net.Listener
-	var svrs []*grpc.Server
 	for i := 0; i < 3; i++ {
 		lis, err := net.Listen("tcp", ports[i])
 		if err != nil {
 			log.Fatalf("failed to listen: %v", err)
 		}
-		listeners = append(listeners, lis)
+		defer lis.Close()
 		s := grpc.NewServer()
-		svrs = append(svrs, s)
 		if i == 2 {
 			pb.RegisterGreeterServer(s, &slowServer{})
 		} else {
@@ -85,13 +81,6 @@ func main() {
 		go s.Serve(lis)
 	}
 
-	/***** Wait for CTRL+C to exit *****/
-	ch := make(chan os.Signal, 1)
-	signal.Notify(ch, os.Interrupt)
-	// Block until a signal is received.
-	<-ch
-	for i := 0; i < 3; i++ {
-		svrs[i].Stop()
-		listeners[i].Close()
-	}
+	/***** Wait for user exiting the program *****/
+	select {}
 }