diff --git a/sentinel-dashboard/src/main/java/com/alibaba/csp/sentinel/dashboard/discovery/SimpleMachineDiscovery.java b/sentinel-dashboard/src/main/java/com/alibaba/csp/sentinel/dashboard/discovery/SimpleMachineDiscovery.java
index a4ab83ac..a21fc355 100755
--- a/sentinel-dashboard/src/main/java/com/alibaba/csp/sentinel/dashboard/discovery/SimpleMachineDiscovery.java
+++ b/sentinel-dashboard/src/main/java/com/alibaba/csp/sentinel/dashboard/discovery/SimpleMachineDiscovery.java
@@ -24,11 +24,13 @@ import java.util.concurrent.ConcurrentMap;
 
 import com.alibaba.csp.sentinel.util.AssertUtil;
 
+import lombok.extern.log4j.Log4j;
 import org.springframework.stereotype.Component;
 
 /**
  * @author leyou
  */
+@Log4j
 @Component
 public class SimpleMachineDiscovery implements MachineDiscovery {
 
@@ -44,6 +46,7 @@ public class SimpleMachineDiscovery implements MachineDiscovery {
 
     @Override
     public boolean removeMachine(String app, String ip, int port) {
+        log.debug("app is " + app);
         AssertUtil.assertNotBlank(app, "app name cannot be blank");
         AppInfo appInfo = apps.get(app);
         if (appInfo != null) {
@@ -54,17 +57,22 @@ public class SimpleMachineDiscovery implements MachineDiscovery {
 
     @Override
     public List<String> getAppNames() {
+
+
+        log.debug("apps.keySet is " + apps.keySet());
         return new ArrayList<>(apps.keySet());
     }
 
     @Override
     public AppInfo getDetailApp(String app) {
+        log.debug("app is " + app);
         AssertUtil.assertNotBlank(app, "app name cannot be blank");
         return apps.get(app);
     }
 
     @Override
     public Set<AppInfo> getBriefApps() {
+        log.debug("apps is " + apps.toString());
         return new HashSet<>(apps.values());
     }