1. Optimize log printing

2. Improve the robustness and readability of your code

naming/src/main/java/com/alibaba/nacos/naming/consistency/ephemeral/distro/DataStore.java

@@ -59,10 +59,11 @@ public class DataStore {
     public Map<String, Datum> batchGet(List<String> keys) {
         Map<String, Datum> map = new HashMap<>(128);
         for (String key : keys) {
-            if (!dataMap.containsKey(key)) {
+            Datum datum = dataMap.get(key);
+            if (datum == null) {
                 continue;
             }
-            map.put(key, dataMap.get(key));
+            map.put(key, datum);
         }
         return map;
     }

naming/src/main/java/com/alibaba/nacos/naming/consistency/ephemeral/distro/DataSyncer.java

@@ -88,34 +88,29 @@ public class DataSyncer {
             return;
         }
 
-        GlobalExecutor.submitDataSync(new Runnable() {
+        GlobalExecutor.submitDataSync(() -> {
-            @Override
+            // 1. check the server
-            public void run() {
-
-                try {
             if (getServers() == null || getServers().isEmpty()) {
                 Loggers.SRV_LOG.warn("try to sync data but server list is empty.");
                 return;
             }
 
             List<String> keys = task.getKeys();
-
             if (Loggers.EPHEMERAL.isDebugEnabled()) {
                 Loggers.EPHEMERAL.debug("sync keys: {}", keys);
             }
 
+            // 2. get the datums by keys and check the datum is empty or not
             Map<String, Datum> datumMap = dataStore.batchGet(keys);
-
             if (datumMap == null || datumMap.isEmpty()) {
                 // clear all flags of this task:
-                        for (String key : task.getKeys()) {
+                for (String key : keys) {
                     taskMap.remove(buildKey(key, task.getTargetServer()));
                 }
                 return;
             }
 
             byte[] data = serializer.serialize(datumMap);
-
             long timestamp = System.currentTimeMillis();
             boolean success = NamingProxy.syncData(data, task.getTargetServer());
             if (!success) {
@@ -131,11 +126,6 @@ public class DataSyncer {
                     taskMap.remove(buildKey(key, task.getTargetServer()));
                 }
             }
-
-                } catch (Exception e) {
-                    Loggers.EPHEMERAL.error("sync data failed.", e);
-                }
-            }
         }, delay);
     }
 
@@ -149,7 +139,6 @@ public class DataSyncer {
             return;
         }
 
-        // TODO may choose other retry policy.
         submit(syncTask, partitionConfig.getSyncRetryDelay());
     }
 
@@ -164,10 +153,6 @@ public class DataSyncer {
 
             try {
 
-                if (Loggers.EPHEMERAL.isDebugEnabled()) {
-                    Loggers.EPHEMERAL.debug("server list is: {}", getServers());
-                }
-
                 // send local timestamps to other servers:
                 Map<String, String> keyChecksums = new HashMap<>(64);
                 for (String key : dataStore.keys()) {
@@ -175,7 +160,11 @@ public class DataSyncer {
                         continue;
                     }
 
-                    keyChecksums.put(key, dataStore.get(key).value.getChecksum());
+                    Datum datum = dataStore.get(key);
+                    if (datum == null) {
+                        continue;
+                    }
+                    keyChecksums.put(key, datum.value.getChecksum());
                 }
 
                 if (keyChecksums.isEmpty()) {

naming/src/main/java/com/alibaba/nacos/naming/consistency/ephemeral/distro/DistroConsistencyServiceImpl.java

@@ -211,6 +211,7 @@ public class DistroConsistencyServiceImpl implements EphemeralConsistencyService
                     // abort the procedure:
                     return;
                 }
+
                 if (!dataStore.contains(entry.getKey()) ||
                     dataStore.get(entry.getKey()).value == null ||
                     !dataStore.get(entry.getKey()).value.getChecksum().equals(entry.getValue())) {

naming/src/main/java/com/alibaba/nacos/naming/consistency/ephemeral/distro/TaskDispatcher.java

@@ -15,7 +15,6 @@
  */
 package com.alibaba.nacos.naming.consistency.ephemeral.distro;
 
-import com.alibaba.fastjson.JSON;
 import com.alibaba.nacos.naming.cluster.servers.Server;
 import com.alibaba.nacos.naming.misc.*;
 import org.apache.commons.lang3.StringUtils;
@@ -125,7 +124,7 @@ public class TaskDispatcher {
                             syncTask.setTargetServer(member.getKey());
 
                             if (Loggers.EPHEMERAL.isDebugEnabled() && StringUtils.isNotBlank(key)) {
-                                Loggers.EPHEMERAL.debug("add sync task: {}", JSON.toJSONString(syncTask));
+                                Loggers.EPHEMERAL.debug("add sync task. task server is {}, and key size {}", syncTask.getTargetServer(), keys.size());
                             }
 
                             dataSyncer.submit(syncTask, 0);

naming/src/main/java/com/alibaba/nacos/naming/controllers/DistroController.java

@@ -38,7 +38,6 @@ import org.springframework.web.bind.annotation.RestController;
 
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
-
 import java.nio.charset.StandardCharsets;
 import java.util.HashMap;
 import java.util.Map;
@@ -69,7 +68,7 @@ public class DistroController {
     private SwitchDomain switchDomain;
 
     @RequestMapping(value = "/datum", method = RequestMethod.PUT)
-    public String onSyncDatum(HttpServletRequest request, HttpServletResponse response) throws Exception {
+    public String onSyncDatum(HttpServletRequest request) throws Exception {
 
         String entity = IOUtils.toString(request.getInputStream(), "UTF-8");
 
@@ -114,7 +113,11 @@ public class DistroController {
         String keySplitter = ",";
         Map<String, Datum> datumMap = new HashMap<>(64);
         for (String key : keys.split(keySplitter)) {
-            datumMap.put(key, consistencyService.get(key));
+            Datum datum = consistencyService.get(key);
+            if (datum == null) {
+                continue;
+            }
+            datumMap.put(key, datum);
         }
         response.getWriter().write(new String(serializer.serialize(datumMap), StandardCharsets.UTF_8));
     }

naming/src/main/java/com/alibaba/nacos/naming/core/Instances.java

@@ -39,9 +39,16 @@ import java.util.Map;
  */
 public class Instances implements Record {
 
-    private String cachedChecksum;
+    private static MessageDigest MESSAGE_DIGEST;
 
-    private long lastCalculateTime = 0L;
+    static {
+        try {
+            MESSAGE_DIGEST = MessageDigest.getInstance("MD5");
+        } catch (NoSuchAlgorithmException e) {
+            Loggers.SRV_LOG.error("error while calculating checksum(md5) for instances", e);
+            MESSAGE_DIGEST = null;
+        }
+    }
 
     private List<Instance> instanceList = new ArrayList<>();
 
@@ -61,15 +68,12 @@ public class Instances implements Record {
     @Override
     @JSONField(serialize = false)
     public String getChecksum() {
-        recalculateChecksum();
+
-        return cachedChecksum;
+        return recalculateChecksum();
     }
 
-    public String getCachedChecksum() {
+    private String recalculateChecksum() {
-        return cachedChecksum;
+        String checksum;
-    }
-
-    private void recalculateChecksum() {
         StringBuilder sb = new StringBuilder();
         Collections.sort(instanceList);
         for (Instance ip : instanceList) {
@@ -78,16 +82,14 @@ public class Instances implements Record {
             sb.append(string);
             sb.append(",");
         }
-        MessageDigest md5;
+
-        try {
+        if (MESSAGE_DIGEST != null) {
-            md5 = MessageDigest.getInstance("MD5");
+            checksum =
-            cachedChecksum =
+                new BigInteger(1, MESSAGE_DIGEST.digest((sb.toString()).getBytes(Charset.forName("UTF-8")))).toString(16);
-                new BigInteger(1, md5.digest((sb.toString()).getBytes(Charset.forName("UTF-8")))).toString(16);
+        } else {
-        } catch (NoSuchAlgorithmException e) {
+            checksum = RandomStringUtils.randomAscii(32);
-            Loggers.SRV_LOG.error("error while calculating checksum(md5) for instances", e);
-            cachedChecksum = RandomStringUtils.randomAscii(32);
         }
-        lastCalculateTime = System.currentTimeMillis();
+        return checksum;
     }
 
     public String convertMap2String(Map<String, String> map) {

naming/src/main/java/com/alibaba/nacos/naming/core/ServiceManager.java

@@ -537,20 +537,17 @@ public class ServiceManager implements RecordListener<Service> {
 
         Datum datum = consistencyService.get(KeyBuilder.buildInstanceListKey(service.getNamespaceId(), service.getName(), ephemeral));
 
-        Map<String, Instance> oldInstanceMap = new HashMap<>(16);
         List<Instance> currentIPs = service.allIPs(ephemeral);
-        Map<String, Instance> map = new ConcurrentHashMap<>(currentIPs.size());
+        Map<String, Instance> currentInstances = new HashMap<>(currentIPs.size());
 
         for (Instance instance : currentIPs) {
-            map.put(instance.toIPAddr(), instance);
+            currentInstances.put(instance.toIPAddr(), instance);
-        }
-        if (datum != null) {
-            oldInstanceMap = setValid(((Instances) datum.value).getInstanceList(), map);
         }
 
-        // use HashMap for deep copy:
+        Map<String, Instance> instanceMap = null;
-        HashMap<String, Instance> instanceMap = new HashMap<>(oldInstanceMap.size());
+        if (datum != null) {
-        instanceMap.putAll(oldInstanceMap);
+            instanceMap = setValid(((Instances) datum.value).getInstanceList(), currentInstances);
+        }
 
         for (Instance instance : ips) {
             if (!service.getClusterMap().containsKey(instance.getClusterName())) {

naming/src/main/java/com/alibaba/nacos/naming/misc/NamingProxy.java

@@ -108,8 +108,7 @@ public class NamingProxy {
     }
 
 
-    public static boolean syncData(byte[] data, String curServer) throws Exception {
+    public static boolean syncData(byte[] data, String curServer) {
-        try {
         Map<String, String> headers = new HashMap<>(128);
 
         headers.put("Client-Version", UtilsAndCommons.SERVER_VERSION);
@@ -118,17 +117,15 @@ public class NamingProxy {
         headers.put("Connection", "Keep-Alive");
         headers.put("Content-Encoding", "gzip");
 
+        try {
             HttpClient.HttpResult result = HttpClient.httpPutLarge("http://" + curServer + RunningConfig.getContextPath()
                 + UtilsAndCommons.NACOS_NAMING_CONTEXT + DATA_ON_SYNC_URL, headers, data);
-
             if (HttpURLConnection.HTTP_OK == result.code) {
                 return true;
             }
-
             if (HttpURLConnection.HTTP_NOT_MODIFIED == result.code) {
                 return true;
             }
-
             throw new IOException("failed to req API:" + "http://" + curServer
                 + RunningConfig.getContextPath()
                 + UtilsAndCommons.NACOS_NAMING_CONTEXT + DATA_ON_SYNC_URL + ". code:"