diff --git a/core/src/main/java/org/apache/spark/shuffle/unsafe/UnsafeShuffleExternalSorter.java b/core/src/main/java/org/apache/spark/shuffle/unsafe/UnsafeShuffleExternalSorter.java
index c4d26288de33d..36f05e3df8753 100644
--- a/core/src/main/java/org/apache/spark/shuffle/unsafe/UnsafeShuffleExternalSorter.java
+++ b/core/src/main/java/org/apache/spark/shuffle/unsafe/UnsafeShuffleExternalSorter.java
@@ -42,9 +42,9 @@
  * <p>
  * Incoming records are appended to data pages. When all records have been inserted (or when the
  * current thread's shuffle memory limit is reached), the in-memory records are sorted according to
- * their partition ids (using a {@link UnsafeShuffleSorter}). The sorted records are then written
- * to a single output file (or multiple files, if we've spilled). The format of the output files is
- * the same as the format of the final output file written by
+ * their partition ids (using a {@link UnsafeShuffleInMemorySorter}). The sorted records are then
+ * written to a single output file (or multiple files, if we've spilled). The format of the output
+ * files is the same as the format of the final output file written by
  * {@link org.apache.spark.shuffle.sort.SortShuffleWriter}: each output partition's records are
  * written as a single serialized, compressed stream that can be read with a new decompression and
  * deserialization stream.
@@ -86,7 +86,7 @@ final class UnsafeShuffleExternalSorter {
   private final LinkedList<SpillInfo> spills = new LinkedList<SpillInfo>();
 
   // All three of these variables are reset after spilling:
-  private UnsafeShuffleSorter sorter;
+  private UnsafeShuffleInMemorySorter sorter;
   private MemoryBlock currentPage = null;
   private long currentPagePosition = -1;
   private long freeSpaceInCurrentPage = 0;
@@ -128,7 +128,7 @@ private void openSorter() throws IOException {
       }
     }
 
-    this.sorter = new UnsafeShuffleSorter(initialSize);
+    this.sorter = new UnsafeShuffleInMemorySorter(initialSize);
   }
 
   /**
@@ -153,7 +153,7 @@ private void writeSpillFile(boolean isSpill) throws IOException {
     }
 
     // This call performs the actual sort.
-    final UnsafeShuffleSorter.UnsafeShuffleSorterIterator sortedRecords =
+    final UnsafeShuffleInMemorySorter.UnsafeShuffleSorterIterator sortedRecords =
       sorter.getSortedIterator();
 
     // Currently, we need to open a new DiskBlockObjectWriter for each partition; we can avoid this
diff --git a/core/src/main/java/org/apache/spark/shuffle/unsafe/UnsafeShuffleSorter.java b/core/src/main/java/org/apache/spark/shuffle/unsafe/UnsafeShuffleInMemorySorter.java
similarity index 97%
rename from core/src/main/java/org/apache/spark/shuffle/unsafe/UnsafeShuffleSorter.java
rename to core/src/main/java/org/apache/spark/shuffle/unsafe/UnsafeShuffleInMemorySorter.java
index f2b90617793e5..6fb87848df38b 100644
--- a/core/src/main/java/org/apache/spark/shuffle/unsafe/UnsafeShuffleSorter.java
+++ b/core/src/main/java/org/apache/spark/shuffle/unsafe/UnsafeShuffleInMemorySorter.java
@@ -21,7 +21,7 @@
 
 import org.apache.spark.util.collection.Sorter;
 
-final class UnsafeShuffleSorter {
+final class UnsafeShuffleInMemorySorter {
 
   private final Sorter<PackedRecordPointer, long[]> sorter;
   private static final class SortComparator implements Comparator<PackedRecordPointer> {
@@ -39,7 +39,7 @@ public int compare(PackedRecordPointer left, PackedRecordPointer right) {
    */
   private int sortBufferInsertPosition = 0;
 
-  public UnsafeShuffleSorter(int initialSize) {
+  public UnsafeShuffleInMemorySorter(int initialSize) {
     assert (initialSize > 0);
     this.sortBuffer = new long[initialSize];
     this.sorter = new Sorter<PackedRecordPointer, long[]>(UnsafeShuffleSortDataFormat.INSTANCE);
diff --git a/core/src/test/java/org/apache/spark/shuffle/unsafe/UnsafeShuffleSorterSuite.java b/core/src/test/java/org/apache/spark/shuffle/unsafe/UnsafeShuffleInMemorySorterSuite.java
similarity index 88%
rename from core/src/test/java/org/apache/spark/shuffle/unsafe/UnsafeShuffleSorterSuite.java
rename to core/src/test/java/org/apache/spark/shuffle/unsafe/UnsafeShuffleInMemorySorterSuite.java
index 3fc73b04888ee..d1c45092693f2 100644
--- a/core/src/test/java/org/apache/spark/shuffle/unsafe/UnsafeShuffleSorterSuite.java
+++ b/core/src/test/java/org/apache/spark/shuffle/unsafe/UnsafeShuffleInMemorySorterSuite.java
@@ -30,7 +30,7 @@
 import org.apache.spark.unsafe.memory.MemoryBlock;
 import org.apache.spark.unsafe.memory.TaskMemoryManager;
 
-public class UnsafeShuffleSorterSuite {
+public class UnsafeShuffleInMemorySorterSuite {
 
   private static String getStringFromDataPage(Object baseObject, long baseOffset, int strLength) {
     final byte[] strBytes = new byte[strLength];
@@ -44,8 +44,8 @@ private static String getStringFromDataPage(Object baseObject, long baseOffset,
 
   @Test
   public void testSortingEmptyInput() {
-    final UnsafeShuffleSorter sorter = new UnsafeShuffleSorter(100);
-    final UnsafeShuffleSorter.UnsafeShuffleSorterIterator iter = sorter.getSortedIterator();
+    final UnsafeShuffleInMemorySorter sorter = new UnsafeShuffleInMemorySorter(100);
+    final UnsafeShuffleInMemorySorter.UnsafeShuffleSorterIterator iter = sorter.getSortedIterator();
     assert(!iter.hasNext());
   }
 
@@ -66,7 +66,7 @@ public void testBasicSorting() throws Exception {
       new TaskMemoryManager(new ExecutorMemoryManager(MemoryAllocator.HEAP));
     final MemoryBlock dataPage = memoryManager.allocatePage(2048);
     final Object baseObject = dataPage.getBaseObject();
-    final UnsafeShuffleSorter sorter = new UnsafeShuffleSorter(4);
+    final UnsafeShuffleInMemorySorter sorter = new UnsafeShuffleInMemorySorter(4);
     final HashPartitioner hashPartitioner = new HashPartitioner(4);
 
     // Write the records into the data page and store pointers into the sorter
@@ -87,7 +87,7 @@ public void testBasicSorting() throws Exception {
     }
 
     // Sort the records
-    final UnsafeShuffleSorter.UnsafeShuffleSorterIterator iter = sorter.getSortedIterator();
+    final UnsafeShuffleInMemorySorter.UnsafeShuffleSorterIterator iter = sorter.getSortedIterator();
     int prevPartitionId = -1;
     Arrays.sort(dataToSort);
     for (int i = 0; i < dataToSort.length; i++) {
@@ -111,7 +111,7 @@ public void testBasicSorting() throws Exception {
 
   @Test
   public void testSortingManyNumbers() throws Exception {
-    UnsafeShuffleSorter sorter = new UnsafeShuffleSorter(4);
+    UnsafeShuffleInMemorySorter sorter = new UnsafeShuffleInMemorySorter(4);
     int[] numbersToSort = new int[128000];
     Random random = new Random(16);
     for (int i = 0; i < numbersToSort.length; i++) {
@@ -120,7 +120,7 @@ public void testSortingManyNumbers() throws Exception {
     }
     Arrays.sort(numbersToSort);
     int[] sorterResult = new int[numbersToSort.length];
-    UnsafeShuffleSorter.UnsafeShuffleSorterIterator iter = sorter.getSortedIterator();
+    UnsafeShuffleInMemorySorter.UnsafeShuffleSorterIterator iter = sorter.getSortedIterator();
     int j = 0;
     while (iter.hasNext()) {
       iter.loadNext();