diff --git a/src/main/java/com/alibaba/druid/support/http/stat/WebAppStat.java b/src/main/java/com/alibaba/druid/support/http/stat/WebAppStat.java
index 775d8eb83e..3034ae9cb7 100644
--- a/src/main/java/com/alibaba/druid/support/http/stat/WebAppStat.java
+++ b/src/main/java/com/alibaba/druid/support/http/stat/WebAppStat.java
@@ -505,6 +505,7 @@ public class WebAppStat {
 
     public List<Map<String, Object>> getSessionStatDataList() {
         List<Map<String, Object>> sessionStatDataList = new ArrayList<Map<String, Object>>(this.sessionStatMap.size());
+        //去除ConcurrentModificationException的异常
         for (WebSessionStat sessionStat : Collections.unmodifiableCollection(this.sessionStatMap.values())) {
             Map<String, Object> sessionStatData = sessionStat.getStatData();