diff --git a/oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/analysis/worker/TopNWorker.java b/oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/analysis/worker/TopNWorker.java
index 0287f07dc66cf201a6a9dbd04705b0261db20a3c..712e99259de6f1ddce6be2e9b35359fdcb9fc91e 100644
--- a/oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/analysis/worker/TopNWorker.java
+++ b/oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/analysis/worker/TopNWorker.java
@@ -30,7 +30,7 @@ import org.apache.skywalking.oap.server.library.module.ModuleDefineHolder;
 import org.slf4j.*;
 
 /**
- * Top N worker is a persistence worker, but no
+ * Top N worker is a persistence worker. Cache and order the data, flush in longer period.
  *
  * @author wusheng, peng-yongsheng
  */