update helloworld
diff --git a/cpp/helloworld/greeter_async_client.cc b/cpp/helloworld/greeter_async_client.cc
index 5fa6ec6..b131005 100644
--- a/cpp/helloworld/greeter_async_client.cc
+++ b/cpp/helloworld/greeter_async_client.cc
@@ -90,22 +90,16 @@
     }
   }
 
-  void Shutdown() { stub_.reset(); }
-
  private:
   std::unique_ptr<Greeter::Stub> stub_;
 };
 
 int main(int argc, char** argv) {
-  grpc_init();
-
   GreeterClient greeter(grpc::CreateChannel(
       "localhost:50051", grpc::InsecureCredentials(), ChannelArguments()));
   std::string user("world");
   std::string reply = greeter.SayHello(user);
   std::cout << "Greeter received: " << reply << std::endl;
 
-  greeter.Shutdown();
-
-  grpc_shutdown();
+  return 0;
 }
diff --git a/cpp/helloworld/greeter_async_server.cc b/cpp/helloworld/greeter_async_server.cc
index 47110a7..2e5343b 100644
--- a/cpp/helloworld/greeter_async_server.cc
+++ b/cpp/helloworld/greeter_async_server.cc
@@ -131,11 +131,8 @@
 };
 
 int main(int argc, char** argv) {
-  grpc_init();
-
   ServerImpl server;
   server.Run();
 
-  grpc_shutdown();
   return 0;
 }
diff --git a/cpp/helloworld/greeter_client.cc b/cpp/helloworld/greeter_client.cc
index 4776cf9..c0aec16 100644
--- a/cpp/helloworld/greeter_client.cc
+++ b/cpp/helloworld/greeter_client.cc
@@ -71,15 +71,11 @@
     }
   }
 
-  void Shutdown() { stub_.reset(); }
-
  private:
   std::unique_ptr<Greeter::Stub> stub_;
 };
 
 int main(int argc, char** argv) {
-  grpc_init();
-
   GreeterClient greeter(
       grpc::CreateChannel("localhost:50051", grpc::InsecureCredentials(),
                           ChannelArguments()));
@@ -87,7 +83,5 @@
   std::string reply = greeter.SayHello(user);
   std::cout << "Greeter received: " << reply << std::endl;
 
-  greeter.Shutdown();
-
-  grpc_shutdown();
+  return 0;
 }
diff --git a/cpp/helloworld/greeter_server.cc b/cpp/helloworld/greeter_server.cc
index a090075..e40bf1b 100644
--- a/cpp/helloworld/greeter_server.cc
+++ b/cpp/helloworld/greeter_server.cc
@@ -73,10 +73,7 @@
 }
 
 int main(int argc, char** argv) {
-  grpc_init();
-
   RunServer();
 
-  grpc_shutdown();
   return 0;
 }