diff --git a/core/src/main/java/org/apache/spark/shuffle/unsafe/UnsafeShuffleWriter.java b/core/src/main/java/org/apache/spark/shuffle/unsafe/UnsafeShuffleWriter.java
index d142cf59d8085..1c875a15687c1 100644
--- a/core/src/main/java/org/apache/spark/shuffle/unsafe/UnsafeShuffleWriter.java
+++ b/core/src/main/java/org/apache/spark/shuffle/unsafe/UnsafeShuffleWriter.java
@@ -17,21 +17,18 @@
 
 package org.apache.spark.shuffle.unsafe;
 
-import org.apache.spark.*;
-import org.apache.spark.unsafe.sort.ExternalSorterIterator;
-import org.apache.spark.unsafe.sort.UnsafeExternalSorter;
+import java.io.File;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+
 import scala.Option;
 import scala.Product2;
 import scala.reflect.ClassTag;
 import scala.reflect.ClassTag$;
 
-import java.io.File;
-import java.io.IOException;
-import java.nio.ByteBuffer;
-import java.util.LinkedList;
-
 import com.esotericsoftware.kryo.io.ByteBufferOutputStream;
 
+import org.apache.spark.*;
 import org.apache.spark.executor.ShuffleWriteMetrics;
 import org.apache.spark.scheduler.MapStatus;
 import org.apache.spark.scheduler.MapStatus$;
@@ -44,10 +41,11 @@
 import org.apache.spark.storage.BlockObjectWriter;
 import org.apache.spark.storage.ShuffleBlockId;
 import org.apache.spark.unsafe.PlatformDependent;
-import org.apache.spark.unsafe.memory.MemoryBlock;
 import org.apache.spark.unsafe.memory.TaskMemoryManager;
-
-import static org.apache.spark.unsafe.sort.UnsafeSorter.*;
+import org.apache.spark.unsafe.sort.ExternalSorterIterator;
+import org.apache.spark.unsafe.sort.UnsafeExternalSorter;
+import static org.apache.spark.unsafe.sort.UnsafeSorter.PrefixComparator;
+import static org.apache.spark.unsafe.sort.UnsafeSorter.RecordComparator;
 
 // IntelliJ gets confused and claims that this class should be abstract, but this actually compiles
 public class UnsafeShuffleWriter<K, V> implements ShuffleWriter<K, V> {
diff --git a/core/src/main/java/org/apache/spark/unsafe/sort/UnsafeSorter.java b/core/src/main/java/org/apache/spark/unsafe/sort/UnsafeSorter.java
index 917cbdb564a15..c69d486705f65 100644
--- a/core/src/main/java/org/apache/spark/unsafe/sort/UnsafeSorter.java
+++ b/core/src/main/java/org/apache/spark/unsafe/sort/UnsafeSorter.java
@@ -176,8 +176,7 @@ public void remove() {
 
   public UnsafeSorterSpillMerger.MergeableIterator getMergeableIterator() {
     sorter.sort(sortBuffer, 0, sortBufferInsertPosition / 2, sortComparator);
-    UnsafeSorterSpillMerger.MergeableIterator iter =
-      new UnsafeSorterSpillMerger.MergeableIterator() {
+    return new UnsafeSorterSpillMerger.MergeableIterator() {
 
       private int position = 0;
       private Object baseObject;
@@ -213,6 +212,5 @@ public long getBaseOffset() {
         return baseOffset;
       }
     };
-    return iter;
   }
 }
diff --git a/core/src/main/java/org/apache/spark/unsafe/sort/UnsafeSorterSpillMerger.java b/core/src/main/java/org/apache/spark/unsafe/sort/UnsafeSorterSpillMerger.java
index 93278d5a26473..bd3f4424724f6 100644
--- a/core/src/main/java/org/apache/spark/unsafe/sort/UnsafeSorterSpillMerger.java
+++ b/core/src/main/java/org/apache/spark/unsafe/sort/UnsafeSorterSpillMerger.java
@@ -18,12 +18,11 @@
 package org.apache.spark.unsafe.sort;
 
 import java.util.Comparator;
-import java.util.Iterator;
 import java.util.PriorityQueue;
 
 import static org.apache.spark.unsafe.sort.UnsafeSorter.*;
 
-public final class UnsafeSorterSpillMerger {
+final class UnsafeSorterSpillMerger {
 
   private final PriorityQueue<MergeableIterator> priorityQueue;
 
@@ -39,13 +38,6 @@ public static abstract class MergeableIterator {
     public abstract long getBaseOffset();
   }
 
-  public static final class RecordAddressAndKeyPrefix {
-    public Object baseObject;
-    public long baseOffset;
-    public int recordLength;
-    public long keyPrefix;
-  }
-
   public UnsafeSorterSpillMerger(
     final RecordComparator recordComparator,
     final UnsafeSorter.PrefixComparator prefixComparator) {
@@ -74,11 +66,10 @@ public void addSpill(MergeableIterator spillReader) {
     priorityQueue.add(spillReader);
   }
 
-  public Iterator<RecordAddressAndKeyPrefix> getSortedIterator() {
-    return new Iterator<RecordAddressAndKeyPrefix>() {
+  public ExternalSorterIterator getSortedIterator() {
+    return new ExternalSorterIterator() {
 
       private MergeableIterator spillReader;
-      private final RecordAddressAndKeyPrefix record = new RecordAddressAndKeyPrefix();
 
       @Override
       public boolean hasNext() {
@@ -86,7 +77,7 @@ public boolean hasNext() {
       }
 
       @Override
-      public RecordAddressAndKeyPrefix next() {
+      public void loadNext() {
         if (spillReader != null) {
           if (spillReader.hasNext()) {
             spillReader.loadNextRecord();
@@ -94,17 +85,10 @@ public RecordAddressAndKeyPrefix next() {
           }
         }
         spillReader = priorityQueue.remove();
-        record.baseObject = spillReader.getBaseObject();
-        record.baseOffset = spillReader.getBaseOffset();
-        record.keyPrefix = spillReader.getPrefix();
-        return record;
-      }
-
-      @Override
-      public void remove() {
-        throw new UnsupportedOperationException();
+        baseObject = spillReader.getBaseObject();
+        baseOffset = spillReader.getBaseOffset();
+        keyPrefix = spillReader.getPrefix();
       }
     };
   }
-
 }
diff --git a/core/src/main/java/org/apache/spark/unsafe/sort/UnsafeSorterSpillReader.java b/core/src/main/java/org/apache/spark/unsafe/sort/UnsafeSorterSpillReader.java
index 894a593d41f3e..3102e5ab3b6f4 100644
--- a/core/src/main/java/org/apache/spark/unsafe/sort/UnsafeSorterSpillReader.java
+++ b/core/src/main/java/org/apache/spark/unsafe/sort/UnsafeSorterSpillReader.java
@@ -17,13 +17,14 @@
 
 package org.apache.spark.unsafe.sort;
 
+import java.io.*;
+
 import com.google.common.io.ByteStreams;
+
 import org.apache.spark.storage.BlockId;
 import org.apache.spark.storage.BlockManager;
 import org.apache.spark.unsafe.PlatformDependent;
 
-import java.io.*;
-
 final class UnsafeSorterSpillReader extends UnsafeSorterSpillMerger.MergeableIterator {
 
   private final File file;
diff --git a/core/src/main/java/org/apache/spark/unsafe/sort/UnsafeSorterSpillWriter.java b/core/src/main/java/org/apache/spark/unsafe/sort/UnsafeSorterSpillWriter.java
index 6085df67d2c2e..33356c3351967 100644
--- a/core/src/main/java/org/apache/spark/unsafe/sort/UnsafeSorterSpillWriter.java
+++ b/core/src/main/java/org/apache/spark/unsafe/sort/UnsafeSorterSpillWriter.java
@@ -17,9 +17,14 @@
 
 package org.apache.spark.unsafe.sort;
 
+import java.io.*;
+import java.nio.ByteBuffer;
+
+import scala.Tuple2;
+import scala.reflect.ClassTag;
+
 import org.apache.spark.executor.ShuffleWriteMetrics;
 import org.apache.spark.serializer.DeserializationStream;
-import org.apache.spark.serializer.JavaSerializerInstance;
 import org.apache.spark.serializer.SerializationStream;
 import org.apache.spark.serializer.SerializerInstance;
 import org.apache.spark.storage.BlockId;
@@ -27,27 +32,23 @@
 import org.apache.spark.storage.BlockObjectWriter;
 import org.apache.spark.storage.TempLocalBlockId;
 import org.apache.spark.unsafe.PlatformDependent;
-import scala.Tuple2;
-import scala.reflect.ClassTag;
-
-import java.io.*;
-import java.nio.ByteBuffer;
 
 final class UnsafeSorterSpillWriter {
 
   private static final int SER_BUFFER_SIZE = 1024 * 1024;  // TODO: tune this
-  public static final int EOF_MARKER = -1;
-  byte[] arr = new byte[SER_BUFFER_SIZE];
+  static final int EOF_MARKER = -1;
+
+  private byte[] arr = new byte[SER_BUFFER_SIZE];
 
   private final File file;
   private final BlockId blockId;
-  BlockObjectWriter writer;
-  DataOutputStream dos;
+  private BlockObjectWriter writer;
+  private DataOutputStream dos;
 
   public UnsafeSorterSpillWriter(
       BlockManager blockManager,
       int fileBufferSize,
-      ShuffleWriteMetrics writeMetrics) throws IOException {
+      ShuffleWriteMetrics writeMetrics) {
     final Tuple2<TempLocalBlockId, File> spilledFileInfo =
       blockManager.diskBlockManager().createTempLocalBlock();
     this.file = spilledFileInfo._2();
@@ -119,6 +120,8 @@ public void write(
   public void close() throws IOException {
     dos.writeInt(EOF_MARKER);
     writer.commitAndClose();
+    writer = null;
+    dos = null;
     arr = null;
   }