diff --git a/core/src/main/scala/kafka/log/s3/ObjectWriter.java b/core/src/main/scala/kafka/log/s3/ObjectWriter.java
index 386bcf0f8f..891f94a723 100644
--- a/core/src/main/scala/kafka/log/s3/ObjectWriter.java
+++ b/core/src/main/scala/kafka/log/s3/ObjectWriter.java
@@ -21,7 +21,6 @@
 import io.netty.buffer.CompositeByteBuf;
 import io.netty.buffer.Unpooled;
 import kafka.log.s3.model.StreamRecordBatch;
-import kafka.log.s3.objects.ObjectManager;
 import kafka.log.s3.objects.ObjectStreamRange;
 import kafka.log.s3.operator.S3Operator;
 import kafka.log.s3.operator.Writer;
@@ -37,15 +36,13 @@
 
 // TODO: memory optimization
 public class ObjectWriter {
-    private int blockSizeThreshold;
-    private int partSizeThreshold;
-    private final S3Operator s3Operator;
+    private final int blockSizeThreshold;
+    private final int partSizeThreshold;
     private final List<DataBlock> waitingUploadBlocks;
     private final List<DataBlock> completedBlocks;
     private IndexBlock indexBlock;
     private final Writer writer;
     private final long objectId;
-    private final String objectKey;
     private long nextDataBlockPosition;
 
     private long size;
@@ -54,8 +51,7 @@ public class ObjectWriter {
 
     public ObjectWriter(long objectId, S3Operator s3Operator, int blockSizeThreshold, int partSizeThreshold) {
         this.objectId = objectId;
-        this.objectKey = ObjectUtils.genKey(0, "todocluster", objectId);
-        this.s3Operator = s3Operator;
+        String objectKey = ObjectUtils.genKey(0, "todocluster", objectId);
         this.blockSizeThreshold = blockSizeThreshold;
         this.partSizeThreshold = partSizeThreshold;
         waitingUploadBlocks = new LinkedList<>();
diff --git a/core/src/main/scala/kafka/log/s3/S3Wal.java b/core/src/main/scala/kafka/log/s3/S3Wal.java
index aed67da1a1..f2b375ef04 100644
--- a/core/src/main/scala/kafka/log/s3/S3Wal.java
+++ b/core/src/main/scala/kafka/log/s3/S3Wal.java
@@ -48,8 +48,7 @@ public class S3Wal implements Wal {
     public S3Wal(ObjectManager objectManager, S3Operator s3Operator) {
         writeBuffer = new ArrayBlockingQueue<>(16384);
         walBatchWriteTask = new WalBatchWriteTask(objectManager, s3Operator);
-        minorCompactTask = new MinorCompactTask(5L * 1024 * 1024 * 1024, 60, 16 * 1024 * 1024
-                , objectManager, s3Operator);
+        minorCompactTask = new MinorCompactTask(5L * 1024 * 1024 * 1024, 60, 16 * 1024 * 1024, objectManager, s3Operator);
         this.objectManager = objectManager;
         this.s3Operator = s3Operator;
     }
diff --git a/core/src/main/scala/kafka/log/s3/SingleWalObjectWriteTask.java b/core/src/main/scala/kafka/log/s3/SingleWalObjectWriteTask.java
index a649b0937b..c2406b9a01 100644
--- a/core/src/main/scala/kafka/log/s3/SingleWalObjectWriteTask.java
+++ b/core/src/main/scala/kafka/log/s3/SingleWalObjectWriteTask.java
@@ -24,7 +24,6 @@
 import kafka.log.s3.objects.CommitWalObjectResponse;
 import kafka.log.s3.objects.ObjectManager;
 import kafka.log.s3.operator.S3Operator;
-import kafka.log.s3.utils.ObjectUtils;
 
 import java.util.Collections;
 import java.util.HashSet;