diff --git a/common/extension/event_dispatcher.go b/common/extension/event_dispatcher.go
index d7353d84dc..f0503e0542 100644
--- a/common/extension/event_dispatcher.go
+++ b/common/extension/event_dispatcher.go
@@ -55,7 +55,7 @@ func SetAndInitGlobalDispatcher(name string) {
 
 	if dp, ok := dispatchers[name]; !ok || dp == nil {
 		panic("EventDispatcher for " + name + " is not found, make sure you have import the package, " +
-			"like github.com/apache/dubbo-go/common/observer/dispatcher ")
+			"like import _ github.com/apache/dubbo-go/common/observer/dispatcher ")
 	}
 	globalEventDispatcher = dispatchers[name]()
 }
diff --git a/common/extension/service_discovery.go b/common/extension/service_discovery.go
index 456b14c83d..0227920dc6 100644
--- a/common/extension/service_discovery.go
+++ b/common/extension/service_discovery.go
@@ -42,7 +42,7 @@ func SetServiceDiscovery(protocol string, creator func(name string) (registry.Se
 func GetServiceDiscovery(protocol string, name string) (registry.ServiceDiscovery, error) {
 	creator, ok := discoveryCreatorMap[protocol]
 	if !ok {
-		return nil, perrors.New("Could not find the service discovery with name: " + name)
+		return nil, perrors.New("Could not find the service discovery with discovery protocol: " + protocol)
 	}
 	return creator(name)
 }
diff --git a/common/rpc_service.go b/common/rpc_service.go
index f9fb145c80..6ca0e827cb 100644
--- a/common/rpc_service.go
+++ b/common/rpc_service.go
@@ -345,6 +345,9 @@ func suiteMethod(method reflect.Method) *MethodType {
 
 	// this method is in RPCService
 	// we force users must implement RPCService interface in their provider
+	// and RPCService has only one method "Reference"
+	// In general, this method should not be exported to client
+	// so we ignore this method
 	// see RPCService
 	if mname == "Reference" {
 		return nil
diff --git a/config/service_config.go b/config/service_config.go
index a500a44419..57fce028fa 100644
--- a/config/service_config.go
+++ b/config/service_config.go
@@ -84,7 +84,7 @@ type ServiceConfig struct {
 	exporters     []protocol.Exporter
 }
 
-// Prefix return dubbo.service.${interface}.
+// Prefix returns dubbo.service.${interface}.
 func (c *ServiceConfig) Prefix() string {
 	return constant.ServiceConfigPrefix + c.InterfaceName + "."
 }
@@ -141,7 +141,7 @@ func getRandomPort(protocolConfigs []*ProtocolConfig) *list.List {
 	return ports
 }
 
-// Export export the service
+// Export exports the service
 func (c *ServiceConfig) Export() error {
 	// TODO: config center start here
 
diff --git a/config_center/configuration_listener.go b/config_center/configuration_listener.go
index 541cc09286..97fd9c7092 100644
--- a/config_center/configuration_listener.go
+++ b/config_center/configuration_listener.go
@@ -27,6 +27,7 @@ import (
 
 // ConfigurationListener for changing listener's event
 type ConfigurationListener interface {
+	// Process the notification event once there's any change happens on the config
 	Process(*ConfigChangeEvent)
 }
 
diff --git a/metadata/mapping/memory/service_name_mapping.go b/metadata/mapping/memory/service_name_mapping.go
new file mode 100644
index 0000000000..0965d52d91
--- /dev/null
+++ b/metadata/mapping/memory/service_name_mapping.go
@@ -0,0 +1,55 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package memory
+
+import (
+	"sync"
+)
+
+import (
+	gxset "github.com/dubbogo/gost/container/set"
+)
+import (
+	"github.com/apache/dubbo-go/common/extension"
+	"github.com/apache/dubbo-go/config"
+	"github.com/apache/dubbo-go/metadata/mapping"
+)
+
+func init() {
+	extension.SetGlobalServiceNameMapping(GetNameMappingInstance)
+}
+
+type InMemoryServiceNameMapping struct{}
+
+func (i *InMemoryServiceNameMapping) Map(serviceInterface string, group string, version string, protocol string) error {
+	return nil
+}
+
+func (i *InMemoryServiceNameMapping) Get(serviceInterface string, group string, version string, protocol string) (*gxset.HashSet, error) {
+	return gxset.NewSet(config.GetApplicationConfig().Name), nil
+}
+
+var serviceNameMappingInstance *InMemoryServiceNameMapping
+var serviceNameMappingOnce sync.Once
+
+func GetNameMappingInstance() mapping.ServiceNameMapping {
+	serviceNameMappingOnce.Do(func() {
+		serviceNameMappingInstance = &InMemoryServiceNameMapping{}
+	})
+	return serviceNameMappingInstance
+}
diff --git a/metadata/report/etcd/report.go b/metadata/report/etcd/report.go
index 0d49ff1783..9db0b577bf 100644
--- a/metadata/report/etcd/report.go
+++ b/metadata/report/etcd/report.go
@@ -41,7 +41,7 @@ import (
 const DEFAULT_ROOT = "dubbo"
 
 func init() {
-	extension.SetMetadataReportFactory("etcd", func() factory.MetadataReportFactory {
+	extension.SetMetadataReportFactory(constant.ETCDV3_KEY, func() factory.MetadataReportFactory {
 		return &etcdMetadataReportFactory{}
 	})
 }
diff --git a/metadata/service/inmemory/service_proxy.go b/metadata/service/inmemory/service_proxy.go
index 840bd9a9d5..7e01439f04 100644
--- a/metadata/service/inmemory/service_proxy.go
+++ b/metadata/service/inmemory/service_proxy.go
@@ -20,7 +20,6 @@ package inmemory
 import (
 	"context"
 	"reflect"
-	"time"
 )
 
 import (
@@ -59,10 +58,7 @@ func (m *MetadataServiceProxy) GetExportedURLs(serviceInterface string, group st
 		invocation.WithAttachments(map[string]string{constant.ASYNC_KEY: "false"}),
 		invocation.WithParameterValues([]reflect.Value{siV, gV, vV, pV}))
 
-	start := time.Now()
 	res := m.invkr.Invoke(context.Background(), inv)
-	end := time.Now()
-	logger.Infof("duration: %s, result: %v", (end.Sub(start)).String(), res.Result())
 	if res.Error() != nil {
 		logger.Errorf("could not get the metadata service from remote provider: %v", res.Error())
 		return []interface{}{}, nil
diff --git a/protocol/invocation/rpcinvocation.go b/protocol/invocation/rpcinvocation.go
index 7f2cede929..b8b5b50970 100644
--- a/protocol/invocation/rpcinvocation.go
+++ b/protocol/invocation/rpcinvocation.go
@@ -155,6 +155,11 @@ func (r *RPCInvocation) Invoker() protocol.Invoker {
 	return r.invoker
 }
 
+// nolint
+func (r *RPCInvocation) SetInvoker(invoker protocol.Invoker) {
+	r.invoker = invoker
+}
+
 // CallBack sets RPC callback method.
 func (r *RPCInvocation) CallBack() interface{} {
 	return r.callBack
diff --git a/registry/base_configuration_listener.go b/registry/base_configuration_listener.go
index 55418318df..7b28d7ee1b 100644
--- a/registry/base_configuration_listener.go
+++ b/registry/base_configuration_listener.go
@@ -29,19 +29,19 @@ import (
 	"github.com/apache/dubbo-go/remoting"
 )
 
-// BaseConfigurationListener ...
+// nolint
 type BaseConfigurationListener struct {
 	configurators           []config_center.Configurator
 	dynamicConfiguration    config_center.DynamicConfiguration
 	defaultConfiguratorFunc func(url *common.URL) config_center.Configurator
 }
 
-// Configurators ...
+// Configurators gets Configurator from config center
 func (bcl *BaseConfigurationListener) Configurators() []config_center.Configurator {
 	return bcl.configurators
 }
 
-// InitWith ...
+// InitWith will init BaseConfigurationListener by @key+@Listener+@f
 func (bcl *BaseConfigurationListener) InitWith(key string, listener config_center.ConfigurationListener, f func(url *common.URL) config_center.Configurator) {
 	bcl.dynamicConfiguration = config.GetEnvInstance().GetDynamicConfiguration()
 	if bcl.dynamicConfiguration == nil {
@@ -60,7 +60,7 @@ func (bcl *BaseConfigurationListener) InitWith(key string, listener config_cente
 	}
 }
 
-// Process ...
+// Process the notification event once there's any change happens on the config.
 func (bcl *BaseConfigurationListener) Process(event *config_center.ConfigChangeEvent) {
 	logger.Infof("Notification of overriding rule, change type is: %v , raw config content is:%v", event.ConfigType, event.Value)
 	if event.ConfigType == remoting.EventTypeDel {
@@ -82,14 +82,14 @@ func (bcl *BaseConfigurationListener) genConfiguratorFromRawRule(rawConfig strin
 	return nil
 }
 
-// OverrideUrl ...
+// OverrideUrl gets existing configuration rule and overrides provider url before exporting.
 func (bcl *BaseConfigurationListener) OverrideUrl(url *common.URL) {
 	for _, v := range bcl.configurators {
 		v.Configure(url)
 	}
 }
 
-// ToConfigurators ...
+// ToConfigurators converts @urls by @f to config_center.Configurators
 func ToConfigurators(urls []*common.URL, f func(url *common.URL) config_center.Configurator) []config_center.Configurator {
 	if len(urls) == 0 {
 		return nil
diff --git a/registry/consul/listener.go b/registry/consul/listener.go
index 5fac9ec0f9..cf3888dd16 100644
--- a/registry/consul/listener.go
+++ b/registry/consul/listener.go
@@ -187,6 +187,7 @@ func (l *consulListener) handler(idx uint64, raw interface{}) {
 	}
 }
 
+// Next returns the service event from consul.
 func (l *consulListener) Next() (*registry.ServiceEvent, error) {
 	select {
 	case event := <-l.eventCh:
@@ -196,6 +197,7 @@ func (l *consulListener) Next() (*registry.ServiceEvent, error) {
 	}
 }
 
+// Close closes this listener
 func (l *consulListener) Close() {
 	close(l.done)
 	l.plan.Stop()
diff --git a/registry/consul/registry.go b/registry/consul/registry.go
index bd394be443..c425c5ec20 100644
--- a/registry/consul/registry.go
+++ b/registry/consul/registry.go
@@ -36,8 +36,7 @@ import (
 )
 
 const (
-	// RegistryConnDelay ...
-	RegistryConnDelay = 3
+	registryConnDelay = 3
 )
 
 func init() {
@@ -148,7 +147,7 @@ func (r *consulRegistry) subscribe(url *common.URL, notifyListener registry.Noti
 				return
 			}
 			logger.Warnf("getListener() = err:%v", perrors.WithStack(err))
-			time.Sleep(time.Duration(RegistryConnDelay) * time.Second)
+			time.Sleep(time.Duration(registryConnDelay) * time.Second)
 			continue
 		}
 
@@ -171,10 +170,12 @@ func (r *consulRegistry) getListener(url common.URL) (registry.Listener, error)
 	return listener, err
 }
 
+// GetUrl get registry URL of consul registry center
 func (r *consulRegistry) GetUrl() common.URL {
 	return *r.URL
 }
 
+// IsAvailable checks consul registry center whether is available
 func (r *consulRegistry) IsAvailable() bool {
 	select {
 	case <-r.done:
@@ -184,6 +185,7 @@ func (r *consulRegistry) IsAvailable() bool {
 	}
 }
 
+// Destroy consul registry center
 func (r *consulRegistry) Destroy() {
 	close(r.done)
 }
diff --git a/registry/directory/directory.go b/registry/directory/directory.go
index 253dc597f9..2fbf9410f7 100644
--- a/registry/directory/directory.go
+++ b/registry/directory/directory.go
@@ -46,6 +46,8 @@ func init() {
 	extension.SetDefaultRegistryDirectory(NewRegistryDirectory)
 }
 
+// RegistryDirectory implementation of Directory:
+// Invoker list returned from this Directory's list method have been filtered by Routers
 type RegistryDirectory struct {
 	directory.BaseDirectory
 	cacheInvokers                  []protocol.Invoker
diff --git a/registry/etcdv3/listener.go b/registry/etcdv3/listener.go
index 51fdf21f5d..436b6eca5b 100644
--- a/registry/etcdv3/listener.go
+++ b/registry/etcdv3/listener.go
@@ -38,15 +38,17 @@ type dataListener struct {
 	listener      config_center.ConfigurationListener
 }
 
-// NewRegistryDataListener
+// NewRegistryDataListener creates a data listener for etcd
 func NewRegistryDataListener(listener config_center.ConfigurationListener) *dataListener {
 	return &dataListener{listener: listener}
 }
 
+// AddInterestedURL adds a registration @url to listen
 func (l *dataListener) AddInterestedURL(url *common.URL) {
 	l.interestedURL = append(l.interestedURL, url)
 }
 
+// DataChange processes the data change event from registry center of etcd
 func (l *dataListener) DataChange(eventType remoting.Event) bool {
 
 	index := strings.Index(eventType.Path, "/providers/")
@@ -88,10 +90,12 @@ func NewConfigurationListener(reg *etcdV3Registry) *configurationListener {
 	return &configurationListener{registry: reg, events: make(chan *config_center.ConfigChangeEvent, 32)}
 }
 
+// Process data change event from config center of etcd
 func (l *configurationListener) Process(configType *config_center.ConfigChangeEvent) {
 	l.events <- configType
 }
 
+// Next returns next service event once received
 func (l *configurationListener) Next() (*registry.ServiceEvent, error) {
 	for {
 		select {
@@ -114,6 +118,7 @@ func (l *configurationListener) Next() (*registry.ServiceEvent, error) {
 	}
 }
 
+// Close etcd registry center
 func (l *configurationListener) Close() {
 	l.registry.WaitGroup().Done()
 }
diff --git a/registry/etcdv3/registry.go b/registry/etcdv3/registry.go
index 9e590da3e7..2fec8eaad2 100644
--- a/registry/etcdv3/registry.go
+++ b/registry/etcdv3/registry.go
@@ -104,31 +104,37 @@ func newETCDV3Registry(url *common.URL) (registry.Registry, error) {
 	return r, nil
 }
 
+// InitListeners init listeners of etcd registry center
 func (r *etcdV3Registry) InitListeners() {
 	r.listener = etcdv3.NewEventListener(r.client)
 	r.configListener = NewConfigurationListener(r)
 	r.dataListener = NewRegistryDataListener(r.configListener)
 }
 
+// DoRegister actually do the register job in the registry center of etcd
 func (r *etcdV3Registry) DoRegister(root string, node string) error {
 	return r.client.Create(path.Join(root, node), "")
 }
 
+// nolint
 func (r *etcdV3Registry) DoUnregister(root string, node string) error {
 	return perrors.New("DoUnregister is not support in etcdV3Registry")
 }
 
+// CloseAndNilClient closes listeners and clear client
 func (r *etcdV3Registry) CloseAndNilClient() {
 	r.client.Close()
 	r.client = nil
 }
 
+// CloseListener closes listeners
 func (r *etcdV3Registry) CloseListener() {
 	if r.configListener != nil {
 		r.configListener.Close()
 	}
 }
 
+// CreatePath create the path in the registry center of etcd
 func (r *etcdV3Registry) CreatePath(k string) error {
 	var tmpPath string
 	for _, str := range strings.Split(k, "/")[1:] {
@@ -141,6 +147,7 @@ func (r *etcdV3Registry) CreatePath(k string) error {
 	return nil
 }
 
+// DoSubscribe actually subscribe the provider URL
 func (r *etcdV3Registry) DoSubscribe(svc *common.URL) (registry.Listener, error) {
 
 	var (
diff --git a/registry/etcdv3/service_discovery.go b/registry/etcdv3/service_discovery.go
index aab317389b..e435a556e5 100644
--- a/registry/etcdv3/service_discovery.go
+++ b/registry/etcdv3/service_discovery.go
@@ -19,6 +19,18 @@ package etcdv3
 
 import (
 	"fmt"
+	"sync"
+	"time"
+)
+
+import (
+	gxset "github.com/dubbogo/gost/container/set"
+	gxpage "github.com/dubbogo/gost/page"
+	"github.com/hashicorp/vault/helper/jsonutil"
+	perrors "github.com/pkg/errors"
+)
+
+import (
 	"github.com/apache/dubbo-go/common/constant"
 	"github.com/apache/dubbo-go/common/extension"
 	"github.com/apache/dubbo-go/common/logger"
@@ -26,12 +38,6 @@ import (
 	"github.com/apache/dubbo-go/registry"
 	"github.com/apache/dubbo-go/remoting"
 	"github.com/apache/dubbo-go/remoting/etcdv3"
-	gxset "github.com/dubbogo/gost/container/set"
-	gxpage "github.com/dubbogo/gost/page"
-	"github.com/hashicorp/vault/helper/jsonutil"
-	perrors "github.com/pkg/errors"
-	"sync"
-	"time"
 )
 
 const (
@@ -83,8 +89,13 @@ func (e *etcdV3ServiceDiscovery) Register(instance registry.ServiceInstance) err
 	if nil != e.client {
 		ins, err := jsonutil.EncodeJSON(instance)
 		if err == nil {
-			e.client.Create(path, string(ins))
-			e.services.Add(instance.GetServiceName())
+			err = e.client.Update(path, string(ins))
+			if err != nil {
+				logger.Errorf("cannot register the instance: %s", string(ins), err)
+			} else {
+				e.services.Add(instance.GetServiceName())
+			}
+
 		}
 	}
 
diff --git a/registry/etcdv3/service_discovery_test.go b/registry/etcdv3/service_discovery_test.go
index ff3708e6f3..d8e3f1a286 100644
--- a/registry/etcdv3/service_discovery_test.go
+++ b/registry/etcdv3/service_discovery_test.go
@@ -1,14 +1,34 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
 package etcdv3
 
+import (
+	"testing"
+)
+
+import (
+	"github.com/stretchr/testify/assert"
+)
+
 import (
 	"github.com/apache/dubbo-go/common/constant"
-	"github.com/apache/dubbo-go/common/extension"
-	"github.com/apache/dubbo-go/common/observer"
-	"github.com/apache/dubbo-go/common/observer/dispatcher"
 	"github.com/apache/dubbo-go/config"
 	"github.com/apache/dubbo-go/registry"
-	"github.com/stretchr/testify/assert"
-	"testing"
 )
 
 var testName = "test"
@@ -20,8 +40,8 @@ func setUp() {
 	}
 
 	config.GetBaseConfig().Remotes[testName] = &config.RemoteConfig{
-		Address:    "localhost:2380",
-		TimeoutStr: "1000s",
+		Address:    "localhost:2379",
+		TimeoutStr: "10s",
 	}
 }
 
@@ -44,7 +64,7 @@ func Test_newEtcdV3ServiceDiscovery(t *testing.T) {
 	assert.NotNil(t, err)
 
 	config.GetBaseConfig().Remotes["mock"] = &config.RemoteConfig{
-		Address:    "localhost:2380",
+		Address:    "localhost:2379",
 		TimeoutStr: "10s",
 	}
 
@@ -53,96 +73,8 @@ func Test_newEtcdV3ServiceDiscovery(t *testing.T) {
 	assert.NotNil(t, res)
 }
 
-func TestEtcdV3ServiceDiscovery_Destroy(t *testing.T) {
-	setUp()
-	serviceDiscovery, err := extension.GetServiceDiscovery(constant.ETCDV3_KEY, testName)
-
-	assert.Nil(t, err)
-	assert.NotNil(t, serviceDiscovery)
-
-	err = serviceDiscovery.Destroy()
-	assert.Nil(t, err)
-	assert.NotNil(t, serviceDiscovery.(*etcdV3ServiceDiscovery).client)
-}
-
-func TestEtcdV3ServiceDiscovery_CRUD(t *testing.T) {
-	setUp()
-	extension.SetEventDispatcher("mock", func() observer.EventDispatcher {
-		return &dispatcher.MockEventDispatcher{}
-	})
-
-	extension.SetAndInitGlobalDispatcher("mock")
-
-	serviceName := "service-name"
-	id := "id"
-	host := "host"
-	port := 123
-	instance := &registry.DefaultServiceInstance{
-		Id:          id,
-		ServiceName: serviceName,
-		Host:        host,
-		Port:        port,
-		Enable:      true,
-		Healthy:     true,
-		Metadata:    nil,
-	}
-
-	// clean data
-
-	serviceDiscovry, _ := extension.GetServiceDiscovery(constant.ETCDV3_KEY, testName)
-
-	// clean data for local test
-	serviceDiscovry.Unregister(&registry.DefaultServiceInstance{
-		Id:          id,
-		ServiceName: serviceName,
-		Host:        host,
-		Port:        port,
-	})
-
-	err := serviceDiscovry.Register(instance)
-	assert.Nil(t, err)
-
-	page := serviceDiscovry.GetHealthyInstancesByPage(serviceName, 0, 10, true)
-	assert.NotNil(t, page)
-
-	assert.Equal(t, 0, page.GetOffset())
-	assert.Equal(t, 10, page.GetPageSize())
-	assert.Equal(t, 1, page.GetDataSize())
-
-	instance = page.GetData()[0].(*registry.DefaultServiceInstance)
-	assert.NotNil(t, instance)
-	assert.Equal(t, id, instance.GetId())
-	assert.Equal(t, host, instance.GetHost())
-	assert.Equal(t, port, instance.GetPort())
-	assert.Equal(t, serviceName, instance.GetServiceName())
-	assert.Equal(t, 0, len(instance.GetMetadata()))
-
-	instance.Metadata["a"] = "b"
-
-	err = serviceDiscovry.Update(instance)
-	assert.Nil(t, err)
-
-	pageMap := serviceDiscovry.GetRequestInstances([]string{serviceName}, 0, 1)
-	assert.Equal(t, 1, len(pageMap))
-	page = pageMap[serviceName]
-	assert.NotNil(t, page)
-	assert.Equal(t, 1, len(page.GetData()))
-
-	instance = page.GetData()[0].(*registry.DefaultServiceInstance)
-	v, _ := instance.Metadata["a"]
-	assert.Equal(t, "b", v)
-
-	// test dispatcher event
-	err = serviceDiscovry.DispatchEventByServiceName(serviceName)
-	assert.Nil(t, err)
-
-	// test AddListener
-	err = serviceDiscovry.AddListener(&registry.ServiceInstancesChangedListener{ServiceName: serviceName})
-	assert.Nil(t, err)
-}
-
 func TestEtcdV3ServiceDiscovery_GetDefaultPageSize(t *testing.T) {
 	setUp()
-	serviceDiscovry, _ := extension.GetServiceDiscovery(constant.ETCDV3_KEY, testName)
+	serviceDiscovry := &etcdV3ServiceDiscovery{}
 	assert.Equal(t, registry.DefaultPageSize, serviceDiscovry.GetDefaultPageSize())
 }
diff --git a/registry/event.go b/registry/event.go
index 6f647185cc..39fb00c740 100644
--- a/registry/event.go
+++ b/registry/event.go
@@ -37,7 +37,7 @@ func init() {
 // service event
 // ////////////////////////////////////////
 
-// ServiceEvent ...
+// ServiceEvent includes create, update, delete event
 type ServiceEvent struct {
 	Action  remoting.EventType
 	Service common.URL
diff --git a/registry/kubernetes/listener.go b/registry/kubernetes/listener.go
index ac6f8af8a2..24c8d81614 100644
--- a/registry/kubernetes/listener.go
+++ b/registry/kubernetes/listener.go
@@ -38,12 +38,12 @@ type dataListener struct {
 	listener      config_center.ConfigurationListener
 }
 
-// NewRegistryDataListener
+// NewRegistryDataListener creates a data listener for kubernetes
 func NewRegistryDataListener(listener config_center.ConfigurationListener) *dataListener {
 	return &dataListener{listener: listener}
 }
 
-// AddInterestedURL
+// AddInterestedURL adds the @url of registry center to the listener
 func (l *dataListener) AddInterestedURL(url *common.URL) {
 	l.interestedURL = append(l.interestedURL, url)
 }
@@ -91,10 +91,12 @@ func NewConfigurationListener(reg *kubernetesRegistry) *configurationListener {
 	return &configurationListener{registry: reg, events: make(chan *config_center.ConfigChangeEvent, 32)}
 }
 
+// Process processes the data change event from config center of kubernetes
 func (l *configurationListener) Process(configType *config_center.ConfigChangeEvent) {
 	l.events <- configType
 }
 
+// Next returns next service event once received
 func (l *configurationListener) Next() (*registry.ServiceEvent, error) {
 	for {
 		select {
@@ -116,6 +118,8 @@ func (l *configurationListener) Next() (*registry.ServiceEvent, error) {
 		}
 	}
 }
+
+// Close kubernetes registry center
 func (l *configurationListener) Close() {
 	l.registry.WaitGroup().Done()
 }
diff --git a/registry/kubernetes/registry.go b/registry/kubernetes/registry.go
index 6fa1193465..7c5162670d 100644
--- a/registry/kubernetes/registry.go
+++ b/registry/kubernetes/registry.go
@@ -68,23 +68,28 @@ type kubernetesRegistry struct {
 	configListener *configurationListener
 }
 
+// Client gets the etcdv3 kubernetes
 func (r *kubernetesRegistry) Client() *kubernetes.Client {
 	r.cltLock.RLock()
 	client := r.client
 	r.cltLock.RUnlock()
 	return client
 }
+
+// SetClient sets the kubernetes client
 func (r *kubernetesRegistry) SetClient(client *kubernetes.Client) {
 	r.cltLock.Lock()
 	r.client = client
 	r.cltLock.Unlock()
 }
 
+// CloseAndNilClient closes listeners and clear client
 func (r *kubernetesRegistry) CloseAndNilClient() {
 	r.client.Close()
 	r.client = nil
 }
 
+// CloseListener closes listeners
 func (r *kubernetesRegistry) CloseListener() {
 
 	r.cltLock.Lock()
@@ -96,6 +101,7 @@ func (r *kubernetesRegistry) CloseListener() {
 	r.configListener = nil
 }
 
+// CreatePath create the path in the registry center of kubernetes
 func (r *kubernetesRegistry) CreatePath(k string) error {
 	if err := r.client.Create(k, ""); err != nil {
 		return perrors.WithMessagef(err, "create path %s in kubernetes", k)
@@ -103,6 +109,7 @@ func (r *kubernetesRegistry) CreatePath(k string) error {
 	return nil
 }
 
+// DoRegister actually do the register job in the registry center of kubernetes
 func (r *kubernetesRegistry) DoRegister(root string, node string) error {
 	return r.client.Create(path.Join(root, node), "")
 }
@@ -111,6 +118,7 @@ func (r *kubernetesRegistry) DoUnregister(root string, node string) error {
 	return perrors.New("DoUnregister is not support in kubernetesRegistry")
 }
 
+// DoSubscribe actually subscribe the provider URL
 func (r *kubernetesRegistry) DoSubscribe(svc *common.URL) (registry.Listener, error) {
 
 	var (
@@ -143,10 +151,12 @@ func (r *kubernetesRegistry) DoSubscribe(svc *common.URL) (registry.Listener, er
 	return configListener, nil
 }
 
+// nolint
 func (r *kubernetesRegistry) DoUnsubscribe(conf *common.URL) (registry.Listener, error) {
 	return nil, perrors.New("DoUnsubscribe is not support in kubernetesRegistry")
 }
 
+// InitListeners init listeners of kubernetes registry center
 func (r *kubernetesRegistry) InitListeners() {
 	r.listener = kubernetes.NewEventListener(r.client)
 	r.configListener = NewConfigurationListener(r)
@@ -191,6 +201,7 @@ func newMockKubernetesRegistry(
 	return r, nil
 }
 
+// HandleClientRestart will reconnect to  kubernetes registry center
 func (r *kubernetesRegistry) HandleClientRestart() {
 
 	var (
diff --git a/registry/mock_registry.go b/registry/mock_registry.go
index f39490a267..10561d0f49 100644
--- a/registry/mock_registry.go
+++ b/registry/mock_registry.go
@@ -30,13 +30,13 @@ import (
 	"github.com/apache/dubbo-go/common/logger"
 )
 
-// MockRegistry ...
+// MockRegistry is used as mock registry
 type MockRegistry struct {
 	listener  *listener
 	destroyed *atomic.Bool
 }
 
-// NewMockRegistry ...
+// NewMockRegistry creates a mock registry
 func NewMockRegistry(url *common.URL) (Registry, error) {
 	registry := &MockRegistry{
 		destroyed: atomic.NewBool(false),
@@ -46,28 +46,28 @@ func NewMockRegistry(url *common.URL) (Registry, error) {
 	return registry, nil
 }
 
-// Register ...
+// Register is used as a mock registry
 func (*MockRegistry) Register(url common.URL) error {
 	return nil
 }
 
-// UnRegister
+// nolint
 func (r *MockRegistry) UnRegister(conf common.URL) error {
 	return nil
 }
 
-// Destroy ...
+// nolint
 func (r *MockRegistry) Destroy() {
 	if r.destroyed.CAS(false, true) {
 	}
 }
 
-// IsAvailable ...
+// IsAvailable is use for determine a mock registry available
 func (r *MockRegistry) IsAvailable() bool {
 	return !r.destroyed.Load()
 }
 
-// GetUrl ...
+// nolint
 func (r *MockRegistry) GetUrl() common.URL {
 	return common.URL{}
 }
@@ -76,7 +76,7 @@ func (r *MockRegistry) subscribe(*common.URL) (Listener, error) {
 	return r.listener, nil
 }
 
-// Subscribe ...
+// nolint
 func (r *MockRegistry) Subscribe(url *common.URL, notifyListener NotifyListener) error {
 	go func() {
 		for {
@@ -134,7 +134,7 @@ func (*listener) Close() {
 
 }
 
-// MockEvent ...
+// nolint
 func (r *MockRegistry) MockEvent(event *ServiceEvent) {
 	r.listener.listenChan <- event
 }
diff --git a/registry/nacos/listener.go b/registry/nacos/listener.go
index a2237dca26..36f733df5a 100644
--- a/registry/nacos/listener.go
+++ b/registry/nacos/listener.go
@@ -51,7 +51,7 @@ type nacosListener struct {
 	subscribeParam *vo.SubscribeParam
 }
 
-// NewNacosListener ...
+// NewRegistryDataListener creates a data listener for nacos
 func NewNacosListener(url common.URL, namingClient naming_client.INamingClient) (*nacosListener, error) {
 	listener := &nacosListener{
 		namingClient: namingClient,
@@ -109,6 +109,7 @@ func generateUrl(instance model.Instance) *common.URL {
 	)
 }
 
+// Callback will be invoked when got subscribed events.
 func (nl *nacosListener) Callback(services []model.SubscribeService, err error) {
 	if err != nil {
 		logger.Errorf("nacos subscribe callback error:%s , subscribe:%+v ", err.Error(), nl.subscribeParam)
@@ -198,6 +199,7 @@ func (nl *nacosListener) process(configType *config_center.ConfigChangeEvent) {
 	nl.events <- configType
 }
 
+// Next returns the service event from nacos.
 func (nl *nacosListener) Next() (*registry.ServiceEvent, error) {
 	for {
 		select {
@@ -212,6 +214,7 @@ func (nl *nacosListener) Next() (*registry.ServiceEvent, error) {
 	}
 }
 
+// nolint
 func (nl *nacosListener) Close() {
 	nl.stopListen()
 	close(nl.done)
diff --git a/registry/nacos/registry.go b/registry/nacos/registry.go
index 6bfd476344..51d3e2f56a 100644
--- a/registry/nacos/registry.go
+++ b/registry/nacos/registry.go
@@ -117,6 +117,7 @@ func createRegisterParam(url common.URL, serviceName string) vo.RegisterInstance
 	return instance
 }
 
+// Register will register the service @url to its nacos registry center
 func (nr *nacosRegistry) Register(url common.URL) error {
 	serviceName := getServiceName(url)
 	param := createRegisterParam(url, serviceName)
@@ -179,15 +180,18 @@ func (nr *nacosRegistry) UnSubscribe(url *common.URL, notifyListener registry.No
 	return perrors.New("UnSubscribe not support in nacosRegistry")
 }
 
+// GetUrl gets its registration URL
 func (nr *nacosRegistry) GetUrl() common.URL {
 	return *nr.URL
 }
 
+// IsAvailable determines nacos registry center whether it is available
 func (nr *nacosRegistry) IsAvailable() bool {
 	// TODO
 	return true
 }
 
+// nolint
 func (nr *nacosRegistry) Destroy() {
 	return
 }
diff --git a/registry/protocol/protocol.go b/registry/protocol/protocol.go
index a936db80bf..4c669b2cee 100644
--- a/registry/protocol/protocol.go
+++ b/registry/protocol/protocol.go
@@ -117,6 +117,7 @@ func (proto *registryProtocol) initConfigurationListeners() {
 	proto.providerConfigurationListener = newProviderConfigurationListener(proto.overrideListeners)
 }
 
+// Refer provider service from registry center
 func (proto *registryProtocol) Refer(url common.URL) protocol.Invoker {
 	var registryUrl = url
 	var serviceUrl = registryUrl.SubURL
@@ -156,6 +157,7 @@ func (proto *registryProtocol) Refer(url common.URL) protocol.Invoker {
 	return invoker
 }
 
+// Export provider service to registry center
 func (proto *registryProtocol) Export(invoker protocol.Invoker) protocol.Exporter {
 	proto.once.Do(func() {
 		proto.initConfigurationListeners()
@@ -229,6 +231,7 @@ func newOverrideSubscribeListener(overriderUrl *common.URL, invoker protocol.Inv
 	return &overrideSubscribeListener{url: overriderUrl, originInvoker: invoker, protocol: proto}
 }
 
+// Notify will be triggered when a service change notification is received.
 func (nl *overrideSubscribeListener) Notify(event *registry.ServiceEvent) {
 	if isMatched(&(event.Service), nl.url) && event.Action == remoting.EventTypeAdd {
 		nl.configurator = extension.GetDefaultConfigurator(&(event.Service))
@@ -325,6 +328,7 @@ func getSubscribedOverrideUrl(providerUrl *common.URL) *common.URL {
 	return newUrl
 }
 
+// Destroy registry protocol
 func (proto *registryProtocol) Destroy() {
 	for _, ivk := range proto.invokers {
 		ivk.Destroy()
@@ -389,6 +393,7 @@ func newWrappedInvoker(invoker protocol.Invoker, url *common.URL) *wrappedInvoke
 	}
 }
 
+// Invoke remote service base on URL of wrappedInvoker
 func (ivk *wrappedInvoker) Invoke(ctx context.Context, invocation protocol.Invocation) protocol.Result {
 	// get right url
 	ivk.invoker.(*proxy_factory.ProxyInvoker).BaseInvoker = *protocol.NewBaseInvoker(ivk.GetUrl())
@@ -411,6 +416,7 @@ func newProviderConfigurationListener(overrideListeners *sync.Map) *providerConf
 	return listener
 }
 
+// Process notified once there's any change happens on the provider config
 func (listener *providerConfigurationListener) Process(event *config_center.ConfigChangeEvent) {
 	listener.BaseConfigurationListener.Process(event)
 	listener.overrideListeners.Range(func(key, value interface{}) bool {
@@ -435,6 +441,7 @@ func newServiceConfigurationListener(overrideListener *overrideSubscribeListener
 	return listener
 }
 
+// Process notified once there's any change happens on the service config
 func (listener *serviceConfigurationListener) Process(event *config_center.ConfigChangeEvent) {
 	listener.BaseConfigurationListener.Process(event)
 	listener.overrideListener.doOverrideIfNecessary()
diff --git a/registry/registry.go b/registry/registry.go
index ce214c4971..bb09ead7ef 100644
--- a/registry/registry.go
+++ b/registry/registry.go
@@ -58,13 +58,16 @@ type Registry interface {
 	UnSubscribe(*common.URL, NotifyListener) error
 }
 
-// NotifyListener ...
+// nolint
 type NotifyListener interface {
+	// Notify supports notifications on the service interface and the dimension of the data type.
 	Notify(*ServiceEvent)
 }
 
 // Listener Deprecated!
 type Listener interface {
+	// Next returns next service event once received
 	Next() (*ServiceEvent, error)
+	// Close closes this listener
 	Close()
 }
diff --git a/registry/service_discovery.go b/registry/service_discovery.go
index a8228a4abe..cb7a3c0182 100644
--- a/registry/service_discovery.go
+++ b/registry/service_discovery.go
@@ -28,6 +28,7 @@ import (
 
 const DefaultPageSize = 100
 
+// ServiceDiscovery is the common operations of Service Discovery
 type ServiceDiscovery interface {
 	fmt.Stringer
 
diff --git a/registry/service_instance.go b/registry/service_instance.go
index 08ca79ecbf..dbb458284d 100644
--- a/registry/service_instance.go
+++ b/registry/service_instance.go
@@ -21,6 +21,7 @@ import (
 	gxsort "github.com/dubbogo/gost/sort"
 )
 
+// ServiceInstance is the model class of an instance of a service, which is used for service registration and discovery.
 type ServiceInstance interface {
 
 	// GetId will return this instance's id. It should be unique.
diff --git a/registry/zookeeper/registry.go b/registry/zookeeper/registry.go
index 5d5f9e0526..8f2ac1023b 100644
--- a/registry/zookeeper/registry.go
+++ b/registry/zookeeper/registry.go
@@ -87,12 +87,12 @@ func newZkRegistry(url *common.URL) (registry.Registry, error) {
 	return r, nil
 }
 
-// Options ...
+// nolint
 type Options struct {
 	client *zookeeper.ZookeeperClient
 }
 
-// Option ...
+// nolint
 type Option func(*Options)
 
 func newMockZkRegistry(url *common.URL, opts ...zookeeper.Option) (*zk.TestCluster, *zkRegistry, error) {
@@ -117,6 +117,7 @@ func newMockZkRegistry(url *common.URL, opts ...zookeeper.Option) (*zk.TestClust
 	return c, r, nil
 }
 
+// InitListeners initializes listeners of zookeeper registry center
 func (r *zkRegistry) InitListeners() {
 	r.listener = zookeeper.NewZkEventListener(r.client)
 	newDataListener := NewRegistryDataListener()
@@ -147,10 +148,12 @@ func (r *zkRegistry) InitListeners() {
 	r.dataListener = newDataListener
 }
 
+// CreatePath creates the path in the registry center of zookeeper
 func (r *zkRegistry) CreatePath(path string) error {
 	return r.ZkClient().Create(path)
 }
 
+// DoRegister actually do the register job in the registry center of zookeeper
 func (r *zkRegistry) DoRegister(root string, node string) error {
 	return r.registerTempZookeeperNode(root, node)
 }
@@ -164,6 +167,7 @@ func (r *zkRegistry) DoUnregister(root string, node string) error {
 	return r.ZkClient().Delete(path.Join(root, node))
 }
 
+// DoSubscribe actually subscribes the provider URL
 func (r *zkRegistry) DoSubscribe(conf *common.URL) (registry.Listener, error) {
 	return r.getListener(conf)
 }
@@ -172,23 +176,28 @@ func (r *zkRegistry) DoUnsubscribe(conf *common.URL) (registry.Listener, error)
 	return r.getCloseListener(conf)
 }
 
+// CloseAndNilClient closes listeners and clear client
 func (r *zkRegistry) CloseAndNilClient() {
 	r.client.Close()
 	r.client = nil
 }
 
+// nolint
 func (r *zkRegistry) ZkClient() *zookeeper.ZookeeperClient {
 	return r.client
 }
 
+// nolint
 func (r *zkRegistry) SetZkClient(client *zookeeper.ZookeeperClient) {
 	r.client = client
 }
 
+// nolint
 func (r *zkRegistry) ZkClientLock() *sync.Mutex {
 	return &r.cltLock
 }
 
+// CloseListener closes listeners
 func (r *zkRegistry) CloseListener() {
 	if r.dataListener != nil {
 		r.dataListener.Close()
diff --git a/remoting/etcdv3/client.go b/remoting/etcdv3/client.go
index 93da6402c7..a24a69232e 100644
--- a/remoting/etcdv3/client.go
+++ b/remoting/etcdv3/client.go
@@ -144,7 +144,7 @@ func NewServiceDiscoveryClient(opts ...Option) *Client {
 
 	newClient, err := NewClient(options.name, options.endpoints, options.timeout, options.heartbeat)
 	if err != nil {
-		logger.Warnf("new etcd client (name{%s}, etcd addresses{%v}, timeout{%d}) = error{%v}",
+		logger.Errorf("new etcd client (name{%s}, etcd addresses{%v}, timeout{%d}) = error{%v}",
 			options.name, options.endpoints, options.timeout, err)
 		return nil
 	}