diff --git a/hugegraph-api/src/main/java/com/baidu/hugegraph/api/traversers/AdamicAdarAPI.java b/hugegraph-api/src/main/java/com/baidu/hugegraph/api/traversers/AdamicAdarAPI.java
index 2f3dc115e7..efd74cab23 100644
--- a/hugegraph-api/src/main/java/com/baidu/hugegraph/api/traversers/AdamicAdarAPI.java
+++ b/hugegraph-api/src/main/java/com/baidu/hugegraph/api/traversers/AdamicAdarAPI.java
@@ -80,9 +80,10 @@ public String get(@Context GraphManager manager,
         Directions dir = Directions.convert(EdgeAPI.parseDirection(direction));
 
         HugeGraph g = graph(manager, graph);
-        PredictionTraverser traverser = new PredictionTraverser(g);
-        double score = traverser.adamicAdar(sourceId, targetId, dir,
-                                            edgeLabel, maxDegree, limit);
-        return JsonUtil.toJson(ImmutableMap.of("adamic_adar", score));
+        try (PredictionTraverser traverser = new PredictionTraverser(g)) {
+            double score = traverser.adamicAdar(sourceId, targetId, dir,
+                                                edgeLabel, maxDegree, limit);
+            return JsonUtil.toJson(ImmutableMap.of("adamic_adar", score));
+        }
     }
 }
diff --git a/hugegraph-api/src/main/java/com/baidu/hugegraph/api/traversers/ResourceAllocationAPI.java b/hugegraph-api/src/main/java/com/baidu/hugegraph/api/traversers/ResourceAllocationAPI.java
index ed729ad1c5..1705c2c84d 100644
--- a/hugegraph-api/src/main/java/com/baidu/hugegraph/api/traversers/ResourceAllocationAPI.java
+++ b/hugegraph-api/src/main/java/com/baidu/hugegraph/api/traversers/ResourceAllocationAPI.java
@@ -80,10 +80,11 @@ public String create(@Context GraphManager manager,
         Directions dir = Directions.convert(EdgeAPI.parseDirection(direction));
 
         HugeGraph g = graph(manager, graph);
-        PredictionTraverser traverser = new PredictionTraverser(g);
-        double score = traverser.resourceAllocation(sourceId, targetId, dir,
-                                                    edgeLabel, maxDegree,
-                                                    limit);
-        return JsonUtil.toJson(ImmutableMap.of("resource_allocation", score));
+        try (PredictionTraverser traverser = new PredictionTraverser(g)) {
+            double score = traverser.resourceAllocation(sourceId, targetId, dir,
+                                                        edgeLabel, maxDegree,
+                                                        limit);
+            return JsonUtil.toJson(ImmutableMap.of("resource_allocation", score));
+        }
     }
 }