diff --git a/hugegraph-core/src/main/java/org/apache/hugegraph/task/ServerInfoManager.java b/hugegraph-core/src/main/java/org/apache/hugegraph/task/ServerInfoManager.java
index e8cccf88e3..ab1ecceca3 100644
--- a/hugegraph-core/src/main/java/org/apache/hugegraph/task/ServerInfoManager.java
+++ b/hugegraph-core/src/main/java/org/apache/hugegraph/task/ServerInfoManager.java
@@ -17,14 +17,13 @@
 
 package org.apache.hugegraph.task;
 
-import static org.apache.hugegraph.backend.query.Query.NO_LIMIT;
-
 import java.util.Collection;
 import java.util.Iterator;
 import java.util.Map;
 import java.util.concurrent.Callable;
 import java.util.concurrent.ExecutorService;
 
+import com.google.common.collect.ImmutableMap;
 import org.apache.hugegraph.HugeException;
 import org.apache.hugegraph.HugeGraph;
 import org.apache.hugegraph.HugeGraphParams;
@@ -49,7 +48,7 @@
 import org.apache.tinkerpop.gremlin.structure.Vertex;
 import org.slf4j.Logger;
 
-import com.google.common.collect.ImmutableMap;
+import static org.apache.hugegraph.backend.query.Query.NO_LIMIT;
 
 public class ServerInfoManager {
 
diff --git a/hugegraph-core/src/main/java/org/apache/hugegraph/traversal/algorithm/CountTraverser.java b/hugegraph-core/src/main/java/org/apache/hugegraph/traversal/algorithm/CountTraverser.java
index 1f23f0a1e4..83b3747e0a 100644
--- a/hugegraph-core/src/main/java/org/apache/hugegraph/traversal/algorithm/CountTraverser.java
+++ b/hugegraph-core/src/main/java/org/apache/hugegraph/traversal/algorithm/CountTraverser.java
@@ -32,6 +32,7 @@
 import org.apache.hugegraph.iterator.FlatMapperIterator;
 import org.apache.hugegraph.structure.HugeEdge;
 import org.apache.hugegraph.util.E;
+import org.apache.tinkerpop.gremlin.structure.util.CloseableIterator;
 
 public class CountTraverser extends HugeTraverser {
 
@@ -93,12 +94,7 @@ public long count(Id source, List<EdgeStep> steps,
 
             return this.count.longValue();
         } finally {
-            if (edges instanceof FlatMapperIterator) {
-                try {
-                    ((FlatMapperIterator<?, ?>)edges).close();
-                } catch (Exception ignored) {
-                }
-            }
+            CloseableIterator.closeIterator(edges);
         }
     }