diff --git a/hugegraph-core/src/main/java/org/apache/hugegraph/backend/tx/EphemeralJobQueue.java b/hugegraph-core/src/main/java/org/apache/hugegraph/backend/tx/EphemeralJobQueue.java
index 42b16a54cb..acb30356aa 100644
--- a/hugegraph-core/src/main/java/org/apache/hugegraph/backend/tx/EphemeralJobQueue.java
+++ b/hugegraph-core/src/main/java/org/apache/hugegraph/backend/tx/EphemeralJobQueue.java
@@ -33,12 +33,11 @@
 
 public class EphemeralJobQueue {
 
-    protected static final Logger LOG = Log.logger(EphemeralJobQueue.class);
+    private static final Logger LOG = Log.logger(EphemeralJobQueue.class);
 
-    public static final int CAPACITY = 2000;
+    private static final int CAPACITY = 2000;
 
-    private final BlockingQueue<EphemeralJob<?>> pendingQueue =
-            new ArrayBlockingQueue<>(CAPACITY);
+    private final BlockingQueue<EphemeralJob<?>> pendingQueue;
 
     private AtomicReference<State> state;
 
@@ -52,6 +51,7 @@ private enum State {
     public EphemeralJobQueue(HugeGraph graph) {
         this.state = new AtomicReference<>(State.INIT);
         this.graph = graph;
+        this.pendingQueue = new ArrayBlockingQueue<>(CAPACITY);
     }
 
     public void add(EphemeralJob<?> job) {
@@ -103,9 +103,9 @@ public static class BatchEphemeralJob extends EphemeralJob<Object> {
 
         private static final int PAGE_SIZE = 100;
         private static final String BATCH_EPHEMERAL_JOB = "batch-ephemeral-job";
-        public static final int MAX_CONSUME_COUNT = EphemeralJobQueue.CAPACITY / 2;
+        private static final int MAX_CONSUME_COUNT = EphemeralJobQueue.CAPACITY / 2;
 
-        WeakReference<EphemeralJobQueue> queueWeakReference;
+        private WeakReference<EphemeralJobQueue> queueWeakReference;
 
         public BatchEphemeralJob(EphemeralJobQueue queue) {
             this.queueWeakReference = new WeakReference<>(queue);
@@ -136,7 +136,7 @@ public Object execute() throws Exception {
                 }
 
                 if (queue.isEmpty() || consumeCount > MAX_CONSUME_COUNT ||
-                          interruptedException != null) {
+                    interruptedException != null) {
                     queue.consumeComplete();
                     stop = true;
                     if (!queue.isEmpty()) {
@@ -216,6 +216,6 @@ public Object call() throws Exception {
     }
 
     public interface Reduce<T> {
-        long reduce(long t1,  T t2);
+        long reduce(T t1,  T t2);
     }
 }
diff --git a/hugegraph-core/src/main/java/org/apache/hugegraph/backend/tx/GraphIndexTransaction.java b/hugegraph-core/src/main/java/org/apache/hugegraph/backend/tx/GraphIndexTransaction.java
index c25076f8f2..39bc6f0421 100644
--- a/hugegraph-core/src/main/java/org/apache/hugegraph/backend/tx/GraphIndexTransaction.java
+++ b/hugegraph-core/src/main/java/org/apache/hugegraph/backend/tx/GraphIndexTransaction.java
@@ -1711,6 +1711,7 @@ private static Query parent(Collection<Query> queries) {
             }
         }
     }
+
     public static class RemoveLeftIndexJob extends EphemeralJob<Long>
                                            implements EphemeralJobQueue.Reduce<Long> {
 
@@ -1961,7 +1962,7 @@ private HugeElement newestElement(HugeElement element) {
         }
 
         @Override
-        public long reduce(long t1, Long t2) {
+        public long reduce(Long t1, Long t2) {
             return t1 + t2;
         }
     }