diff --git a/client/src/main/java/org/apache/rocketmq/client/consumer/DefaultLitePullConsumer.java b/client/src/main/java/org/apache/rocketmq/client/consumer/DefaultLitePullConsumer.java
index 74d6f3455f..440e37e499 100644
--- a/client/src/main/java/org/apache/rocketmq/client/consumer/DefaultLitePullConsumer.java
+++ b/client/src/main/java/org/apache/rocketmq/client/consumer/DefaultLitePullConsumer.java
@@ -447,10 +447,12 @@ public class DefaultLitePullConsumer extends ClientConfig implements LitePullCon
         this.offsetStore = offsetStore;
     }
 
+    @Override
     public boolean isUnitMode() {
         return unitMode;
     }
 
+    @Override
     public void setUnitMode(boolean isUnitMode) {
         this.unitMode = isUnitMode;
     }
diff --git a/client/src/main/java/org/apache/rocketmq/client/consumer/DefaultMQPullConsumer.java b/client/src/main/java/org/apache/rocketmq/client/consumer/DefaultMQPullConsumer.java
index 1c3f3da4d6..4784e72e16 100644
--- a/client/src/main/java/org/apache/rocketmq/client/consumer/DefaultMQPullConsumer.java
+++ b/client/src/main/java/org/apache/rocketmq/client/consumer/DefaultMQPullConsumer.java
@@ -434,10 +434,12 @@ public class DefaultMQPullConsumer extends ClientConfig implements MQPullConsume
         return defaultMQPullConsumerImpl;
     }
 
+    @Override
     public boolean isUnitMode() {
         return unitMode;
     }
 
+    @Override
     public void setUnitMode(boolean isUnitMode) {
         this.unitMode = isUnitMode;
     }
diff --git a/client/src/main/java/org/apache/rocketmq/client/consumer/DefaultMQPushConsumer.java b/client/src/main/java/org/apache/rocketmq/client/consumer/DefaultMQPushConsumer.java
index 8e1c8d15af..b9a82e0109 100644
--- a/client/src/main/java/org/apache/rocketmq/client/consumer/DefaultMQPushConsumer.java
+++ b/client/src/main/java/org/apache/rocketmq/client/consumer/DefaultMQPushConsumer.java
@@ -185,7 +185,7 @@ public class DefaultMQPushConsumer extends ClientConfig implements MQPushConsume
      * Consider the {@code pullBatchSize}, the instantaneous value may exceed the limit
      *
      * <p>
-     * The size of a message only measured by message body, so it's not accurate
+     * The size(MB) of a message only measured by message body, so it's not accurate
      */
     private int pullThresholdSizeForQueue = 100;
 
@@ -417,7 +417,7 @@ public class DefaultMQPushConsumer extends ClientConfig implements MQPushConsume
     @Override
     public void setUseTLS(boolean useTLS) {
         super.setUseTLS(useTLS);
-        if (traceDispatcher != null && traceDispatcher instanceof AsyncTraceDispatcher) {
+        if (traceDispatcher instanceof AsyncTraceDispatcher) {
             ((AsyncTraceDispatcher) traceDispatcher).getTraceProducer().setUseTLS(useTLS);
         }
     }
@@ -860,10 +860,12 @@ public class DefaultMQPushConsumer extends ClientConfig implements MQPushConsume
         this.postSubscriptionWhenPull = postSubscriptionWhenPull;
     }
 
+    @Override
     public boolean isUnitMode() {
         return unitMode;
     }
 
+    @Override
     public void setUnitMode(boolean isUnitMode) {
         this.unitMode = isUnitMode;
     }
diff --git a/client/src/main/java/org/apache/rocketmq/client/impl/consumer/DefaultMQPullConsumerImpl.java b/client/src/main/java/org/apache/rocketmq/client/impl/consumer/DefaultMQPullConsumerImpl.java
index eed5fa43f0..7319fdad74 100644
--- a/client/src/main/java/org/apache/rocketmq/client/impl/consumer/DefaultMQPullConsumerImpl.java
+++ b/client/src/main/java/org/apache/rocketmq/client/impl/consumer/DefaultMQPullConsumerImpl.java
@@ -367,8 +367,10 @@ public class DefaultMQPullConsumerImpl implements MQConsumerInner {
                     } catch (Exception e) {
                         log.error("parse subscription error", e);
                     }
-                    ms.setSubVersion(0L);
-                    result.add(ms);
+                    if (ms != null) {
+                        ms.setSubVersion(0L);
+                        result.add(ms);
+                    }
                 }
             }
         }
diff --git a/client/src/main/java/org/apache/rocketmq/client/producer/DefaultMQProducer.java b/client/src/main/java/org/apache/rocketmq/client/producer/DefaultMQProducer.java
index 02287dd539..0d17d4db8f 100644
--- a/client/src/main/java/org/apache/rocketmq/client/producer/DefaultMQProducer.java
+++ b/client/src/main/java/org/apache/rocketmq/client/producer/DefaultMQProducer.java
@@ -38,9 +38,7 @@ import org.apache.rocketmq.common.MixAll;
 import org.apache.rocketmq.common.message.Message;
 import org.apache.rocketmq.common.message.MessageBatch;
 import org.apache.rocketmq.common.message.MessageClientIDSetter;
-import org.apache.rocketmq.common.message.MessageDecoder;
 import org.apache.rocketmq.common.message.MessageExt;
-import org.apache.rocketmq.common.message.MessageId;
 import org.apache.rocketmq.common.message.MessageQueue;
 import org.apache.rocketmq.common.protocol.ResponseCode;
 import org.apache.rocketmq.common.topic.TopicValidator;
@@ -264,7 +262,7 @@ public class DefaultMQProducer extends ClientConfig implements MQProducer {
     @Override
     public void setUseTLS(boolean useTLS) {
         super.setUseTLS(useTLS);
-        if (traceDispatcher != null && traceDispatcher instanceof AsyncTraceDispatcher) {
+        if (traceDispatcher instanceof AsyncTraceDispatcher) {
             ((AsyncTraceDispatcher) traceDispatcher).getTraceProducer().setUseTLS(useTLS);
         }
     }
@@ -896,9 +894,8 @@ public class DefaultMQProducer extends ClientConfig implements MQProducer {
     public MessageExt viewMessage(String topic,
         String msgId) throws RemotingException, MQBrokerException, InterruptedException, MQClientException {
         try {
-            MessageId oldMsgId = MessageDecoder.decodeMessageId(msgId);
             return this.viewMessage(msgId);
-        } catch (Exception e) {
+        } catch (Exception ignored) {
         }
         return this.defaultMQProducerImpl.queryMessageByUniqKey(withNamespace(topic), msgId);
     }
diff --git a/common/src/main/java/org/apache/rocketmq/common/CountDownLatch2.java b/common/src/main/java/org/apache/rocketmq/common/CountDownLatch2.java
index 9c95fff7bb..4e43e5ce3d 100644
--- a/common/src/main/java/org/apache/rocketmq/common/CountDownLatch2.java
+++ b/common/src/main/java/org/apache/rocketmq/common/CountDownLatch2.java
@@ -172,10 +172,12 @@ public class CountDownLatch2 {
             return getState();
         }
 
+        @Override
         protected int tryAcquireShared(int acquires) {
             return (getState() == 0) ? 1 : -1;
         }
 
+        @Override
         protected boolean tryReleaseShared(int releases) {
             // Decrement count; signal when transition to zero
             for (; ; ) {