Fix https://issues.apache.org/jira/browse/ROCKETMQ-25

client/src/main/java/org/apache/rocketmq/client/impl/MQAdminImpl.java

@@ -23,6 +23,9 @@ import java.util.List;
 import java.util.Set;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.TimeUnit;
+import java.util.concurrent.locks.ReadWriteLock;
+import java.util.concurrent.locks.ReentrantReadWriteLock;
+
 import org.apache.rocketmq.client.QueryResult;
 import org.apache.rocketmq.client.exception.MQBrokerException;
 import org.apache.rocketmq.client.exception.MQClientException;
@@ -285,6 +288,7 @@ public class MQAdminImpl {
             if (!brokerAddrs.isEmpty()) {
                 final CountDownLatch countDownLatch = new CountDownLatch(brokerAddrs.size());
                 final List<QueryResult> queryResultList = new LinkedList<QueryResult>();
+                final ReadWriteLock lock = new ReentrantReadWriteLock(false);
 
                 for (String addr : brokerAddrs) {
                     try {
@@ -318,7 +322,12 @@ public class MQAdminImpl {
                                                         MessageDecoder.decodes(ByteBuffer.wrap(response.getBody()), true);
 
                                                     QueryResult qr = new QueryResult(responseHeader.getIndexLastUpdateTimestamp(), wrappers);
-                                                    queryResultList.add(qr);
+                                                    try {
+                                                        lock.writeLock().lock();
+                                                        queryResultList.add(qr);
+                                                    } finally {
+                                                        lock.writeLock().unlock();
+                                                    }
                                                     break;
                                                 }
                                                 default:

tools/src/main/java/org/apache/rocketmq/tools/command/message/QueryMsgByKeySubCommand.java

@@ -69,7 +69,7 @@ public class QueryMsgByKeySubCommand implements SubCommand {
         }
     }
 
-    void queryByKey(final DefaultMQAdminExt admin, final String topic, final String key)
+    private void queryByKey(final DefaultMQAdminExt admin, final String topic, final String key)
         throws MQClientException, InterruptedException {
         admin.start();