一、前置
如果不了解go + grpc 调用方式和实现细节，可以参考上一篇文章 golang grpc配置使用实战教程
涉及技术点
技术点版本描述golang1.19基础版本grpcv1.41.0gRPC golang包etcd server3.5.0注册中心etcd clientv3.5.8客户端服务发现和负载均衡
服务注册
服务注册依赖etcd的 key-value操作，key作为gRPC服务唯一标识，value存储元数据信息。服务自动续期依赖etcd的lease操作，实现自动服务续期
服务发现
使用watch命令监控指定前缀的key，处理新增和删除事件，实现服务上下线
负载均衡
使用etcd客户端实现负载均衡，获取服务器gRPC IP端口列表后，客户端进行负载均衡
二、代码实现
目录结构说明
. ├── client │ └── client.go ├── etcd │ └── naming.go ├── go.mod ├── go.sum ├── proto │ ├── helloworld.pb.go │ ├── helloworld.proto │ └── helloworld_grpc.pb.go └── server └── server.go
client 客户端相关代码实现，根据注册中心服务列表和负载均衡算法，发起grpc调用。etcd 使用etcd client 实现一个简易的命名服务，进行服务注册、发现、下线等操作proto grpc服务接口定义，主要是使用 protoc 命令生成的模板代码。server 服务端代码实现，启动服务并注册到etcd。
先给出 go.mod 依赖
module example.com/ggrpc
go 1.19
require (
go.etcd.io/etcd/client/v3 v3.5.8
google.golang.org/grpc v1.41.0 // 这里版本需要和etcd匹配，不然编译失败
google.golang.org/protobuf v1.26.0
)
require (
github.com/coreos/go-semver v0.3.0 // indirect
github.com/coreos/go-systemd/v22 v22.3.2 // indirect
github.com/gogo/protobuf v1.3.2 // indirect
github.com/golang/protobuf v1.5.2 // indirect
go.etcd.io/etcd/api/v3 v3.5.8 // indirect
go.etcd.io/etcd/client/pkg/v3 v3.5.8 // indirect
go.uber.org/atomic v1.7.0 // indirect
go.uber.org/multierr v1.6.0 // indirect
go.uber.org/zap v1.17.0 // indirect
golang.org/x/net v0.0.0-20210405180319-a5a99cb37ef4 // indirect
golang.org/x/sys v0.0.0-20210603081109-ebe580a85c40 // indirect
golang.org/x/text v0.3.5 // indirect
google.golang.org/genproto v0.0.0-20210602131652-f16073e35f0c // indirect
)
细节实现
Naming 命名服务
package etcd
import (
"context"
"encoding/json"
"fmt"
clientv3 "go.etcd.io/etcd/client/v3"
"go.etcd.io/etcd/client/v3/naming/endpoints"
"go.etcd.io/etcd/client/v3/naming/resolver"
gresolver "google.golang.org/grpc/resolver"
"log"
)
const (
nameServicePrefix = "my-grpc"
// 默认的租赁时间
defLeaseSecond = 30
)
// 保存已经注册的服务
var serviceMap map[string]*EndpointUnit
// 服务元数据信息
type Endpoint struct {
Name string `json:"name"`
Addr string `json:"addr"`
Port int
Version string `json:"version"`
}
// 服务元数据信息
type EndpointUnit struct {
Name string `json:"name"`
LeaseID clientv3.LeaseID
E Endpoint
}
// 命名服务结构体
type NamingService struct {
EtcdUrl string
Name string
MTarget string
Client *clientv3.Client
manager endpoints.Manager
}
// 创建一个新的命名服务
func NewNamingService(protocol, etcdHost string, etcdPort int, serviceName string) (*NamingService, error) {
url := fmt.Sprintf("%s://%s:%d", protocol, etcdHost, etcdPort)
client, err := clientv3.NewFromURL(url)
if err != nil {
return nil, err
}
target := fmt.Sprintf("%s/%s", nameServicePrefix, serviceName)
// etcd的endpoints管理
manager, err := endpoints.NewManager(client, target)
if err != nil {
return nil, err
}
ns := NamingService{
EtcdUrl: url,
Name: serviceName,
MTarget: target,
manager: manager,
Client: client,
}
serviceMap = make(map[string]*EndpointUnit)
return &ns, nil
}
// 从本地etcd创建
func NewLocalDefNamingService(serviceName string) (*NamingService, error) {
return NewNamingService("http", "localhost", 2379, serviceName)
}
func (naming *NamingService) GetFullServerName(name string, leaseID clientv3.LeaseID) string {
return fmt.Sprintf("%s/%s/%d", naming.MTarget, name, leaseID)
}
func (naming *NamingService) GetPathServerName(name string) string {
return fmt.Sprintf("%s/%s", naming.MTarget, name)
}
// 添加/注册新的服务
func (naming *NamingService) AddEndpoint(e Endpoint) error {
b, _ := json.Marshal(e)
ep := endpoints.Endpoint{
Addr: fmt.Sprintf("%s:%d", e.Addr, e.Port),
Metadata: string(b), // 这里有个坑，必须传入字符串，没来得及看原因
}
// 在etcd创建一个续期的lease对象
lease, err := naming.Client.Grant(context.TODO(), defLeaseSecond)
if err != nil {
return err
}
key := naming.GetFullServerName(e.Name, lease.ID)
// 向etcd注册一个Endpoint并绑定续期
err = naming.manager.AddEndpoint(context.TODO(), key, ep, clientv3.WithLease(lease.ID))
if err != nil {
return err
}
log.Println("AddEndpoint success:", key)
// 开启自动续期KeepAlive
ch, err := naming.Client.KeepAlive(context.TODO(), lease.ID)
if err != nil {
return err
}
// 这个方法会异步打印出每次续期调用的日志
go func() {
for {
ka := <-ch
log.Println("ttl:", ka.ID, ka.TTL)
}
}()
serviceMap[e.Name] = &EndpointUnit{Name: e.Name, LeaseID: lease.ID, E: e}
return nil
}
// 移除一个服务
func (naming *NamingService) DelEndpoint(name string) error {
eu := serviceMap[name]
if eu == nil {
return nil
}
err := naming.manager.DeleteEndpoint(context.TODO(), naming.GetFullServerName(name, eu.LeaseID))
if err != nil {
log.Fatalf("Delete endpoint error %v", err)
return err
}
_, err = naming.Client.Revoke(context.TODO(), eu.LeaseID)
if err != nil {
log.Fatalf("Revoke lease error %v", err)
return err
}
delete(serviceMap, name)
log.Printf("DeleteEndpoint [%s] success\n", name)
return nil
}
// 移除所有服务
func (naming *NamingService) DelAllEndpoint() {
for k := range serviceMap {
err := naming.DelEndpoint(k)
if err != nil {
log.Fatalln("Ignore Failure Continue...")
}
}
}
// 创建一个etcdResolver用于客户端发现服务
func (naming *NamingService) NewEtcdResolver() (gresolver.Builder, error) {
etcdResolver, err := resolver.NewBuilder(naming.Client)
if err != nil {
log.Fatalf("Etcd resolver error %v", err)
return nil, err
}
return etcdResolver, nil
}
服务端实现
package main
import (
"context"
"example.com/ggrpc/etcd"
"flag"
"fmt"
"log"
"net"
"os"
"os/signal"
"syscall"
"time"
pb "example.com/ggrpc/proto"
"google.golang.org/grpc"
)
var (
port = flag.Int("port", 8000, "The server port")
)
const testServerName = "s1"
// 定义一个server实现UnimplementedGreeterServer
// UnimplementedGreeterServer 是第四步自动生成的，可以打开对应文件查看
type server struct {
pb.UnimplementedGreeterServer
}
// server 重写SayHello方法，做业务处理
func (s *server) SayHello(c context.Context, req *pb.HelloRequest) (*pb.HelloReply, error) {
log.Printf("接收到客户端的消息: %v", req.GetName())
time.Sleep(time.Second)
ms := fmt.Sprintf("好的[%d]收到,%s %s", *port, req.GetName(), time.Now())
log.Printf("回复客户端的消息: %s", ms)
return &pb.HelloReply{Message: ms}, nil
}
func main() {
// 解析命令行参数
flag.Parse()
// 监听本地tcp端口
lis, err := net.Listen("tcp", fmt.Sprintf(":%d", *port))
if err != nil {
log.Fatalf("failed to listen: %v", err)
}
// 创建一个grpc Server服务对象,Handler非必传
// s := grpc.NewServer() // 可以直接创建对象
s := grpc.NewServer()
// 注册服务
pb.RegisterGreeterServer(s, &server{})
// 注册ETCD
service, err := etcd.NewLocalDefNamingService("my1")
if err != nil {
log.Fatalf("failed to create NamingService: %v", err)
}
err = service.AddEndpoint(etcd.Endpoint{
Addr: "localhost",
Name: testServerName,
Port: *port,
Version: "1.0.0",
})
if err != nil {
log.Fatalf("failed to reg etcd: %v", err)
}
// 启动RPC并监听
log.Printf("server listening at %v", lis.Addr())
go func() {
if err := s.Serve(lis); err != nil {
log.Fatalf("failed to serve: %v", err)
service.DelAllEndpoint()
}
}()
// 等待关闭信号
quit := make(chan os.Signal)
// kill (no param) default send syscanll.SIGTERM
// kill -2 is syscall.SIGINT
// kill -9 is syscall. SIGKILL but can"t be catch, so don't need add it
signal.Notify(quit, syscall.SIGINT, syscall.SIGTERM)
<-quit
fmt.Printf("Shutdown Server ... \r\n")
// 停止grpc服务
s.GracefulStop()
// 删除etcd注册信息
service.DelAllEndpoint()
fmt.Printf("Graceful Shutdown Server success\r\n")
}
客户端实现
package main
import (
"context"
"example.com/ggrpc/etcd"
pb "example.com/ggrpc/proto"
"flag"
"google.golang.org/grpc"
"log"
"time"
)
//var serAddr = flag.String("addr", "localhost:8000", "the address to connect to")
const etcdDialPrefix = "etcd://localhost:2379/"
func main() {
// 解析命令行参数
flag.Parse()
service, err := etcd.NewLocalDefNamingService("my1")
if err != nil {
log.Fatalf("Create naming service error: %v", err)
}
resolver, err := service.NewEtcdResolver()
if err != nil {
log.Fatalf("Create etcd resolver error: %v", err)
}
// 连接服务端
conn, err := grpc.Dial(etcdDialPrefix+service.GetPathServerName("s1"), grpc.WithInsecure(), grpc.WithResolvers(resolver),
grpc.WithDefaultServiceConfig(`{"loadBalancingPolicy":"round_robin"}`))
if err != nil {
log.Fatalf("Conn server error: %v", err)
}
log.Printf("Conn success: %v", conn.GetState())
// 执行完方法自动关闭资源
defer func() {
err := conn.Close()
if err != nil {
log.Fatalf("Close conn error: %v", err)
return
}
log.Println("Close conn success")
}()
// 创建客户端
c := pb.NewGreeterClient(conn)
log.Println("5秒中之后调用SayHello方法")
time.Sleep(time.Second * 5)
num := 10
for i := 0; i < num; i++ {
// 创建2秒超时ctx
ctx, _ := context.WithTimeout(context.Background(), time.Second*2)
// 发起RPC请求
log.Println("开始调用SayHello方法")
res, err := c.SayHello(ctx, &pb.HelloRequest{Name: "一号"})
if err != nil {
log.Fatalf("请求失败: %v", err)
}
log.Printf("请求结果: %s", res.GetMessage())
}
// 睡眠一会再结束
log.Println("3秒后结束，客户端自动断开连接")
time.Sleep(time.Second * 3)
}
proto 代码
proto 代码可以自己生成，这里只是给出本项目的测试代码
helloworld.pb.go
// 使用的语法协议版本 proto3
// Code generated by protoc-gen-go. DO NOT EDIT.
// versions:
// protoc-gen-go v1.28.1
// protoc v3.18.2
// source: helloworld.proto
package proto
import (
protoreflect "google.golang.org/protobuf/reflect/protoreflect"
protoimpl "google.golang.org/protobuf/runtime/protoimpl"
reflect "reflect"
sync "sync"
)
const (
// Verify that this generated code is sufficiently up-to-date.
_ = protoimpl.EnforceVersion(20 - protoimpl.MinVersion)
// Verify that runtime/protoimpl is sufficiently up-to-date.
_ = protoimpl.EnforceVersion(protoimpl.MaxVersion - 20)
)
// 定义请求对象
type HelloRequest struct {
state protoimpl.MessageState
sizeCache protoimpl.SizeCache
unknownFields protoimpl.UnknownFields
Name string `protobuf:"bytes,1,opt,name=name,proto3" json:"name,omitempty"`
}
func (x *HelloRequest) Reset() {
*x = HelloRequest{}
if protoimpl.UnsafeEnabled {
mi := &file_helloworld_proto_msgTypes[0]
ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
ms.StoreMessageInfo(mi)
}
}
func (x *HelloRequest) String() string {
return protoimpl.X.MessageStringOf(x)
}
func (*HelloRequest) ProtoMessage() {}
func (x *HelloRequest) ProtoReflect() protoreflect.Message {
mi := &file_helloworld_proto_msgTypes[0]
if protoimpl.UnsafeEnabled && x != nil {
ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
if ms.LoadMessageInfo() == nil {
ms.StoreMessageInfo(mi)
}
return ms
}
return mi.MessageOf(x)
}
// Deprecated: Use HelloRequest.ProtoReflect.Descriptor instead.
func (*HelloRequest) Descriptor() ([]byte, []int) {
return file_helloworld_proto_rawDescGZIP(), []int{0}
}
func (x *HelloRequest) GetName() string {
if x != nil {
return x.Name
}
return ""
}
// 定义返回对象
type HelloReply struct {
state protoimpl.MessageState
sizeCache protoimpl.SizeCache
unknownFields protoimpl.UnknownFields
Message string `protobuf:"bytes,1,opt,name=message,proto3" json:"message,omitempty"`
}
func (x *HelloReply) Reset() {
*x = HelloReply{}
if protoimpl.UnsafeEnabled {
mi := &file_helloworld_proto_msgTypes[1]
ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
ms.StoreMessageInfo(mi)
}
}
func (x *HelloReply) String() string {
return protoimpl.X.MessageStringOf(x)
}
func (*HelloReply) ProtoMessage() {}
func (x *HelloReply) ProtoReflect() protoreflect.Message {
mi := &file_helloworld_proto_msgTypes[1]
if protoimpl.UnsafeEnabled && x != nil {
ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
if ms.LoadMessageInfo() == nil {
ms.StoreMessageInfo(mi)
}
return ms
}
return mi.MessageOf(x)
}
// Deprecated: Use HelloReply.ProtoReflect.Descriptor instead.
func (*HelloReply) Descriptor() ([]byte, []int) {
return file_helloworld_proto_rawDescGZIP(), []int{1}
}
func (x *HelloReply) GetMessage() string {
if x != nil {
return x.Message
}
return ""
}
var File_helloworld_proto protoreflect.FileDescriptor
var file_helloworld_proto_rawDesc = []byte{
0x0a, 0x10, 0x68, 0x65, 0x6c, 0x6c, 0x6f, 0x77, 0x6f, 0x72, 0x6c, 0x64, 0x2e, 0x70, 0x72, 0x6f,
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0x0a, 0x48, 0x65, 0x6c, 0x6c, 0x6f, 0x52, 0x65, 0x70, 0x6c, 0x79, 0x12, 0x18, 0x0a, 0x07, 0x6d,
0x65, 0x73, 0x73, 0x61, 0x67, 0x65, 0x18, 0x01, 0x20, 0x01, 0x28, 0x09, 0x52, 0x07, 0x6d, 0x65,
0x73, 0x73, 0x61, 0x67, 0x65, 0x32, 0x3f, 0x0a, 0x07, 0x47, 0x72, 0x65, 0x65, 0x74, 0x65, 0x72,
0x12, 0x34, 0x0a, 0x08, 0x53, 0x61, 0x79, 0x48, 0x65, 0x6c, 0x6c, 0x6f, 0x12, 0x13, 0x2e, 0x70,
0x72, 0x6f, 0x74, 0x6f, 0x2e, 0x48, 0x65, 0x6c, 0x6c, 0x6f, 0x52, 0x65, 0x71, 0x75, 0x65, 0x73,
0x74, 0x1a, 0x11, 0x2e, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x2e, 0x48, 0x65, 0x6c, 0x6c, 0x6f, 0x52,
0x65, 0x70, 0x6c, 0x79, 0x22, 0x00, 0x42, 0x0a, 0x5a, 0x08, 0x2e, 0x2f, 0x3b, 0x70, 0x72, 0x6f,
0x74, 0x6f, 0x62, 0x06, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x33,
}
var (
file_helloworld_proto_rawDescOnce sync.Once
file_helloworld_proto_rawDescData = file_helloworld_proto_rawDesc
)
func file_helloworld_proto_rawDescGZIP() []byte {
file_helloworld_proto_rawDescOnce.Do(func() {
file_helloworld_proto_rawDescData = protoimpl.X.CompressGZIP(file_helloworld_proto_rawDescData)
})
return file_helloworld_proto_rawDescData
}
var file_helloworld_proto_msgTypes = make([]protoimpl.MessageInfo, 2)
var file_helloworld_proto_goTypes = []interface{}{
(*HelloRequest)(nil), // 0: proto.HelloRequest
(*HelloReply)(nil), // 1: proto.HelloReply
}
var file_helloworld_proto_depIdxs = []int32{
0, // 0: proto.Greeter.SayHello:input_type -> proto.HelloRequest
1, // 1: proto.Greeter.SayHello:output_type -> proto.HelloReply
1, // [1:2] is the sub-list for method output_type
0, // [0:1] is the sub-list for method input_type
0, // [0:0] is the sub-list for extension type_name
0, // [0:0] is the sub-list for extension extendee
0, // [0:0] is the sub-list for field type_name
}
func init() { file_helloworld_proto_init() }
func file_helloworld_proto_init() {
if File_helloworld_proto != nil {
return
}
if !protoimpl.UnsafeEnabled {
file_helloworld_proto_msgTypes[0].Exporter = func(v interface{}, i int) interface{} {
switch v := v.(*HelloRequest); i {
case 0:
return &v.state
case 1:
return &v.sizeCache
case 2:
return &v.unknownFields
default:
return nil
}
}
file_helloworld_proto_msgTypes[1].Exporter = func(v interface{}, i int) interface{} {
switch v := v.(*HelloReply); i {
case 0:
return &v.state
case 1:
return &v.sizeCache
case 2:
return &v.unknownFields
default:
return nil
}
}
}
type x struct{}
out := protoimpl.TypeBuilder{
File: protoimpl.DescBuilder{
GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
RawDescriptor: file_helloworld_proto_rawDesc,
NumEnums: 0,
NumMessages: 2,
NumExtensions: 0,
NumServices: 1,
},
GoTypes: file_helloworld_proto_goTypes,
DependencyIndexes: file_helloworld_proto_depIdxs,
MessageInfos: file_helloworld_proto_msgTypes,
}.Build()
File_helloworld_proto = out.File
file_helloworld_proto_rawDesc = nil
file_helloworld_proto_goTypes = nil
file_helloworld_proto_depIdxs = nil
}
helloworld_grpc.pb.go
// Code generated by protoc-gen-go-grpc. DO NOT EDIT.
// versions:
// - protoc-gen-go-grpc v1.2.0
// - protoc v3.18.2
// source: helloworld.proto
package proto
import (
context "context"
grpc "google.golang.org/grpc"
codes "google.golang.org/grpc/codes"
status "google.golang.org/grpc/status"
)
// This is a compile-time assertion to ensure that this generated file
// is compatible with the grpc package it is being compiled against.
// Requires gRPC-Go v1.32.0 or later.
const _ = grpc.SupportPackageIsVersion7
// GreeterClient is the client API for Greeter service.
//
// For semantics around ctx use and closing/ending streaming RPCs, please refer to https://pkg.go.dev/google.golang.org/grpc/?tab=doc#ClientConn.NewStream.
type GreeterClient interface {
// 定义SayHello方法，接受HelloRequest消息， 并返回HelloReply消息
SayHello(ctx context.Context, in *HelloRequest, opts ...grpc.CallOption) (*HelloReply, error)
}
type greeterClient struct {
cc grpc.ClientConnInterface
}
func NewGreeterClient(cc grpc.ClientConnInterface) GreeterClient {
return &greeterClient{cc}
}
func (c *greeterClient) SayHello(ctx context.Context, in *HelloRequest, opts ...grpc.CallOption) (*HelloReply, error) {
out := new(HelloReply)
err := c.cc.Invoke(ctx, "/proto.Greeter/SayHello", in, out, opts...)
if err != nil {
return nil, err
}
return out, nil
}
// GreeterServer is the server API for Greeter service.
// All implementations must embed UnimplementedGreeterServer
// for forward compatibility
type GreeterServer interface {
// 定义SayHello方法，接受HelloRequest消息， 并返回HelloReply消息
SayHello(context.Context, *HelloRequest) (*HelloReply, error)
mustEmbedUnimplementedGreeterServer()
}
// UnimplementedGreeterServer must be embedded to have forward compatible implementations.
type UnimplementedGreeterServer struct {
}
func (UnimplementedGreeterServer) SayHello(context.Context, *HelloRequest) (*HelloReply, error) {
return nil, status.Errorf(codes.Unimplemented, "method SayHello not implemented")
}
func (UnimplementedGreeterServer) mustEmbedUnimplementedGreeterServer() {}
// UnsafeGreeterServer may be embedded to opt out of forward compatibility for this service.
// Use of this interface is not recommended, as added methods to GreeterServer will
// result in compilation errors.
type UnsafeGreeterServer interface {
mustEmbedUnimplementedGreeterServer()
}
func RegisterGreeterServer(s grpc.ServiceRegistrar, srv GreeterServer) {
s.RegisterService(&Greeter_ServiceDesc, srv)
}
func _Greeter_SayHello_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
in := new(HelloRequest)
if err := dec(in); err != nil {
return nil, err
}
if interceptor == nil {
return srv.(GreeterServer).SayHello(ctx, in)
}
info := &grpc.UnaryServerInfo{
Server: srv,
FullMethod: "/proto.Greeter/SayHello",
}
handler := func(ctx context.Context, req interface{}) (interface{}, error) {
return srv.(GreeterServer).SayHello(ctx, req.(*HelloRequest))
}
return interceptor(ctx, in, info, handler)
}
// Greeter_ServiceDesc is the grpc.ServiceDesc for Greeter service.
// It's only intended for direct use with grpc.RegisterService,
// and not to be introspected or modified (even as a copy)
var Greeter_ServiceDesc = grpc.ServiceDesc{
ServiceName: "proto.Greeter",
HandlerType: (*GreeterServer)(nil),
Methods: []grpc.MethodDesc{
{
MethodName: "SayHello",
Handler: _Greeter_SayHello_Handler,
},
},
Streams: []grpc.StreamDesc{},
Metadata: "helloworld.proto",
}
三、测试
启动etcd
启动两个服务端
go run .\server\server.go
023/05/13 13:46:20 AddEndpoint success: my-grpc/my1/s1/7587870565126837256
2023/05/13 13:46:20 server listening at [::]:8000
2023/05/13 13:46:21 ttl: 7587870565126837256 30
go run .\server\server.go -port 8001
2023/05/13 13:47:03 AddEndpoint success: my-grpc/my1/s1/7587870565126837259
2023/05/13 13:47:03 server listening at [::]:8001
2023/05/13 13:47:03 ttl: 7587870565126837259 30
查看etcd中注册的服务
lizheng@lz-x:/mnt/d/dev/go/workspace/my-grpc$ etcdctl get my-grpc --prefix
my-grpc/my1/s1/7587870565126837256
{"Op":0,"Addr":"localhost:8000","Metadata":"{\"name\":\"s1\",\"addr\":\"localhost\",\"Port\":8000,\"version\":\"1.0.0\"}"}
my-grpc/my1/s1/7587870565126837259
{"Op":0,"Addr":"localhost:8001","Metadata":"{\"name\":\"s1\",\"addr\":\"localhost\",\"Port\":8001,\"version\":\"1.0.0\"}"}
启动客户端进行测试
PS D:\dev\go\workspace\my-grpc> go run .\client\client.go
2023/05/13 13:49:41 Conn success: IDLE
2023/05/13 13:49:41 5秒中之后调用SayHello方法
2023/05/13 13:49:46 开始调用SayHello方法
2023/05/13 13:49:47 请求结果: 好的[8001]收到,一号 2023-05-13 13:49:47.8763026 +0800 CST m=+164.396410901
2023/05/13 13:49:47 开始调用SayHello方法
2023/05/13 13:49:48 请求结果: 好的[8000]收到,一号 2023-05-13 13:49:48.8924889 +0800 CST m=+208.647296501
2023/05/13 13:49:48 开始调用SayHello方法
2023/05/13 13:49:49 请求结果: 好的[8001]收到,一号 2023-05-13 13:49:49.8945126 +0800 CST m=+166.414620901
2023/05/13 13:49:49 开始调用SayHello方法
2023/05/13 13:49:50 请求结果: 好的[8000]收到,一号 2023-05-13 13:49:50.9095842 +0800 CST m=+210.664391801
2023/05/13 13:49:50 开始调用SayHello方法
2023/05/13 13:49:51 请求结果: 好的[8001]收到,一号 2023-05-13 13:49:51.9276213 +0800 CST m=+168.447729601
2023/05/13 13:49:51 开始调用SayHello方法
2023/05/13 13:49:52 请求结果: 好的[8000]收到,一号 2023-05-13 13:49:52.9444446 +0800 CST m=+212.699252201
2023/05/13 13:49:52 开始调用SayHello方法
2023/05/13 13:49:53 请求结果: 好的[8001]收到,一号 2023-05-13 13:49:53.9605415 +0800 CST m=+170.480649801
2023/05/13 13:49:53 开始调用SayHello方法
2023/05/13 13:49:54 请求结果: 好的[8000]收到,一号 2023-05-13 13:49:54.9625634 +0800 CST m=+214.717371001
2023/05/13 13:49:54 开始调用SayHello方法
2023/05/13 13:49:55 请求结果: 好的[8001]收到,一号 2023-05-13 13:49:55.9772376 +0800 CST m=+172.497345901
2023/05/13 13:49:55 开始调用SayHello方法
2023/05/13 13:49:56 请求结果: 好的[8000]收到,一号 2023-05-13 13:49:56.9792537 +0800 CST m=+216.734061301
2023/05/13 13:49:56 3秒后结束，客户端自动断开连接
2023/05/13 13:49:59 Close conn success
可以看出实现了自动负载均衡，如果此时停止一个服务可以自动切换识别
四、结语
项目是demo实例工程，提供实现思路和简单方案，有很多不足之处和潜在问题，多多指出！
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