grpc one connection vs multiple connections (one: 13.8s, multi: 17s)

multi.go

package main

import (
	"log"
	"os"
	"sync"
	"time"

	"golang.org/x/net/context"
	"google.golang.org/grpc"
	pb "google.golang.org/grpc/examples/helloworld/helloworld"
)

const (
	address     = "localhost:50051"
	defaultName = "world"
)

func main() {
	// Set up a connection to the server.

	var cs [1000]pb.GreeterClient
	for i := 0; i < 1000; i++ {
		conn, err := grpc.Dial(address, grpc.WithInsecure(), grpc.WithBlock())
		if err != nil {
			log.Fatalf("did not connect: %v", err)
		}
		//defer conn.Close()
		c := pb.NewGreeterClient(conn)
		cs[i] = c
	}
	//log.Printf("clients: %+v", cs)

	// Contact the server and print out its response.
	name := defaultName
	if len(os.Args) > 1 {
		name = os.Args[1]
	}

	var wg sync.WaitGroup
	begin := time.Now()
	for index := 0; index < 1000; index++ {
		wg.Add(1)
		go func(id int) {
			defer wg.Done()
			c := cs[id]
			for j := 0; j < 1000; j++ {
				ctx, cancel := context.WithTimeout(context.Background(), time.Second)
				defer cancel()
				_, err := c.SayHello(ctx, &pb.HelloRequest{Name: name})
				if err != nil {
					log.Printf("could not greet: %v", err)
				} else {
					// log.Printf("Greeting: %s", r.Message)
				}
			}
			//log.Printf("done: %v", id)
		}(index)
	}
	wg.Wait()
	end := time.Now()
	dur := 	end.Sub(begin)
	log.Printf("duration: %v", dur)
}

one.go

package main

import (
	"golang.org/x/net/context"
	"log"
	"os"
	"sync"
	"time"

	"google.golang.org/grpc"
	pb "google.golang.org/grpc/examples/helloworld/helloworld"
)

const (
	address     = "localhost:50051"
	defaultName = "world"
)

func main() {
	// Set up a connection to the server.
	conn, err := grpc.Dial(address, grpc.WithInsecure(), grpc.WithBlock())
	if err != nil {
		log.Fatalf("did not connect: %v", err)
	}
	defer conn.Close()
	c := pb.NewGreeterClient(conn)

	// Contact the server and print out its response.
	name := defaultName
	if len(os.Args) > 1 {
		name = os.Args[1]
	}

	var wg sync.WaitGroup
	begin := time.Now()
	for index := 0; index < 1000; index++ {
		wg.Add(1)
		go func(id int) {
			defer wg.Done()
			for j := 0; j < 1000; j++ {
				ctx, cancel := context.WithTimeout(context.Background(), time.Second)
				defer cancel()
				_, err := c.SayHello(ctx, &pb.HelloRequest{Name: name})
				if err != nil {
					log.Printf("could not greet: %v", err)
				} else {
					// log.Printf("Greeting: %s", r.Message)
				}
			}
			//log.Printf("done: %v", id)
		}(index)
	}
	wg.Wait()
	end := time.Now()
	dur := 	end.Sub(begin)
	log.Printf("duration: %v", dur)
}

server.go

package main

import (
	"log"
	"net"

	"golang.org/x/net/context"
	"google.golang.org/grpc"
	pb "google.golang.org/grpc/examples/helloworld/helloworld"
	"google.golang.org/grpc/reflection"
)

const (
	port = ":50051"
)

// server is used to implement helloworld.GreeterServer.
type server struct{}

// SayHello implements helloworld.GreeterServer
func (s *server) SayHello(ctx context.Context, in *pb.HelloRequest) (*pb.HelloReply, error) {
	return &pb.HelloReply{Message: "Hello " + in.Name}, nil
}

func main() {
	lis, err := net.Listen("tcp", port)
	if err != nil {
		log.Fatalf("failed to listen: %v", err)
	}
	s := grpc.NewServer()
	pb.RegisterGreeterServer(s, &server{})
	// Register reflection service on gRPC server.
	reflection.Register(s)
	if err := s.Serve(lis); err != nil {
		log.Fatalf("failed to serve: %v", err)
	}
}