diff --git a/hadoop-mapreduce-project/CHANGES.txt b/hadoop-mapreduce-project/CHANGES.txt
index 0e33d3c16db..a38fb974237 100644
--- a/hadoop-mapreduce-project/CHANGES.txt
+++ b/hadoop-mapreduce-project/CHANGES.txt
@@ -50,6 +50,9 @@ Release 2.0.3-alpha - Unreleased
 
     MAPREDUCE-4949. Enable multiple pi jobs to run in parallel. (sandyr via tucu)
 
+    MAPREDUCE-4809. Change visibility of classes for pluggable sort changes. 
+    (masokan via tucu)
+
   OPTIMIZATIONS
 
   BUG FIXES
diff --git a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/MapTask.java b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/MapTask.java
index 16fb4d21452..d2ac399810f 100644
--- a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/MapTask.java
+++ b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/MapTask.java
@@ -34,6 +34,8 @@ import java.util.concurrent.locks.ReentrantLock;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
 import org.apache.hadoop.fs.FSDataInputStream;
 import org.apache.hadoop.fs.FSDataOutputStream;
 import org.apache.hadoop.fs.FileSystem;
@@ -71,7 +73,9 @@ import org.apache.hadoop.util.StringInterner;
 import org.apache.hadoop.util.StringUtils;
 
 /** A Map task. */
-class MapTask extends Task {
+@InterfaceAudience.LimitedPrivate({"MapReduce"})
+@InterfaceStability.Unstable
+public class MapTask extends Task {
   /**
    * The size of each record in the index file for the map-outputs.
    */
diff --git a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/Task.java b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/Task.java
index 562dcbe9d44..f983a8d386e 100644
--- a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/Task.java
+++ b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapred/Task.java
@@ -583,9 +583,9 @@ abstract public class Task implements Writable, Configurable {
     return status;
   }
 
-  @InterfaceAudience.Private
+  @InterfaceAudience.LimitedPrivate({"MapReduce"})
   @InterfaceStability.Unstable
-  protected class TaskReporter 
+  public class TaskReporter 
       extends org.apache.hadoop.mapreduce.StatusReporter
       implements Runnable, Reporter {
     private TaskUmbilicalProtocol umbilical;
@@ -1465,9 +1465,9 @@ abstract public class Task implements Writable, Configurable {
     return reducerContext;
   }
 
-  @InterfaceAudience.Private
+  @InterfaceAudience.LimitedPrivate({"MapReduce"})
   @InterfaceStability.Unstable
-  protected static abstract class CombinerRunner<K,V> {
+  public static abstract class CombinerRunner<K,V> {
     protected final Counters.Counter inputCounter;
     protected final JobConf job;
     protected final TaskReporter reporter;
@@ -1485,13 +1485,13 @@ abstract public class Task implements Writable, Configurable {
      * @param iterator the key/value pairs to use as input
      * @param collector the output collector
      */
-    abstract void combine(RawKeyValueIterator iterator, 
+    public abstract void combine(RawKeyValueIterator iterator, 
                           OutputCollector<K,V> collector
                          ) throws IOException, InterruptedException, 
                                   ClassNotFoundException;
 
     @SuppressWarnings("unchecked")
-    static <K,V> 
+    public static <K,V> 
     CombinerRunner<K,V> create(JobConf job,
                                TaskAttemptID taskId,
                                Counters.Counter inputCounter,
@@ -1541,7 +1541,7 @@ abstract public class Task implements Writable, Configurable {
     }
 
     @SuppressWarnings("unchecked")
-    protected void combine(RawKeyValueIterator kvIter,
+    public void combine(RawKeyValueIterator kvIter,
                            OutputCollector<K,V> combineCollector
                            ) throws IOException {
       Reducer<K,V,K,V> combiner = 
@@ -1610,7 +1610,7 @@ abstract public class Task implements Writable, Configurable {
 
     @SuppressWarnings("unchecked")
     @Override
-    void combine(RawKeyValueIterator iterator, 
+    public void combine(RawKeyValueIterator iterator, 
                  OutputCollector<K,V> collector
                  ) throws IOException, InterruptedException,
                           ClassNotFoundException {
diff --git a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/task/reduce/ExceptionReporter.java b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/task/reduce/ExceptionReporter.java
index f893cec5b1a..34a9a42b6b5 100644
--- a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/task/reduce/ExceptionReporter.java
+++ b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/task/reduce/ExceptionReporter.java
@@ -17,9 +17,14 @@
  */
 package org.apache.hadoop.mapreduce.task.reduce;
 
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+
 /**
  * An interface for reporting exceptions to other threads
  */
-interface ExceptionReporter {
+@InterfaceAudience.LimitedPrivate({"MapReduce"})
+@InterfaceStability.Unstable
+public interface ExceptionReporter {
   void reportException(Throwable t);
 }
diff --git a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/task/reduce/MapHost.java b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/task/reduce/MapHost.java
index 7c5e621c5cc..935931dcefd 100644
--- a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/task/reduce/MapHost.java
+++ b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/task/reduce/MapHost.java
@@ -20,9 +20,14 @@ package org.apache.hadoop.mapreduce.task.reduce;
 import java.util.ArrayList;
 import java.util.List;
 
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+
 import org.apache.hadoop.mapreduce.TaskAttemptID;
 
-class MapHost {
+@InterfaceAudience.LimitedPrivate({"MapReduce"})
+@InterfaceStability.Unstable
+public class MapHost {
   
   public static enum State {
     IDLE,               // No map outputs available
diff --git a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/task/reduce/MapOutput.java b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/task/reduce/MapOutput.java
index aab0cccc793..fbe7096abfd 100644
--- a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/task/reduce/MapOutput.java
+++ b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/task/reduce/MapOutput.java
@@ -24,6 +24,8 @@ import java.util.concurrent.atomic.AtomicInteger;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.FileSystem;
 import org.apache.hadoop.fs.LocalDirAllocator;
@@ -33,7 +35,9 @@ import org.apache.hadoop.mapred.JobConf;
 import org.apache.hadoop.mapred.MapOutputFile;
 import org.apache.hadoop.mapreduce.TaskAttemptID;
 
-class MapOutput<K,V> {
+@InterfaceAudience.LimitedPrivate({"MapReduce"})
+@InterfaceStability.Unstable
+public class MapOutput<K,V> {
   private static final Log LOG = LogFactory.getLog(MapOutput.class);
   private static AtomicInteger ID = new AtomicInteger(0);
   
@@ -62,7 +66,7 @@ class MapOutput<K,V> {
   
   private final boolean primaryMapOutput;
   
-  MapOutput(TaskAttemptID mapId, MergeManager<K,V> merger, long size, 
+  public MapOutput(TaskAttemptID mapId, MergeManager<K,V> merger, long size, 
             JobConf conf, LocalDirAllocator localDirAllocator,
             int fetcher, boolean primaryMapOutput, MapOutputFile mapOutputFile)
          throws IOException {
@@ -87,7 +91,7 @@ class MapOutput<K,V> {
     this.primaryMapOutput = primaryMapOutput;
   }
   
-  MapOutput(TaskAttemptID mapId, MergeManager<K,V> merger, int size, 
+  public MapOutput(TaskAttemptID mapId, MergeManager<K,V> merger, int size, 
             boolean primaryMapOutput) {
     this.id = ID.incrementAndGet();
     this.mapId = mapId;
diff --git a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/task/reduce/MergeManager.java b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/task/reduce/MergeManager.java
index e658be47c95..0b5d57cc915 100644
--- a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/task/reduce/MergeManager.java
+++ b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/task/reduce/MergeManager.java
@@ -60,8 +60,8 @@ import org.apache.hadoop.util.ReflectionUtils;
 
 import com.google.common.annotations.VisibleForTesting;
 
-@SuppressWarnings(value={"unchecked"})
-@InterfaceAudience.Private
+@SuppressWarnings(value={"unchecked", "deprecation"})
+@InterfaceAudience.LimitedPrivate({"MapReduce"})
 @InterfaceStability.Unstable
 public class MergeManager<K, V> {
   
diff --git a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/task/reduce/Shuffle.java b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/task/reduce/Shuffle.java
index fc22979797a..047e6435ccf 100644
--- a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/task/reduce/Shuffle.java
+++ b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/task/reduce/Shuffle.java
@@ -39,7 +39,7 @@ import org.apache.hadoop.mapreduce.MRJobConfig;
 import org.apache.hadoop.mapreduce.TaskAttemptID;
 import org.apache.hadoop.util.Progress;
 
-@InterfaceAudience.LimitedPrivate("mapreduce")
+@InterfaceAudience.LimitedPrivate({"MapReduce"})
 @InterfaceStability.Unstable
 @SuppressWarnings({"unchecked", "rawtypes"})
 public class Shuffle<K, V> implements ShuffleConsumerPlugin<K, V>, ExceptionReporter {
diff --git a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/task/reduce/ShuffleClientMetrics.java b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/task/reduce/ShuffleClientMetrics.java
index d327aa45946..92c69a60a5a 100644
--- a/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/task/reduce/ShuffleClientMetrics.java
+++ b/hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/task/reduce/ShuffleClientMetrics.java
@@ -17,6 +17,9 @@
  */
 package org.apache.hadoop.mapreduce.task.reduce;
 
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+
 import org.apache.hadoop.mapred.JobConf;
 import org.apache.hadoop.mapreduce.MRJobConfig;
 import org.apache.hadoop.mapreduce.TaskAttemptID;
@@ -25,7 +28,9 @@ import org.apache.hadoop.metrics.MetricsRecord;
 import org.apache.hadoop.metrics.MetricsUtil;
 import org.apache.hadoop.metrics.Updater;
 
-class ShuffleClientMetrics implements Updater {
+@InterfaceAudience.LimitedPrivate({"MapReduce"})
+@InterfaceStability.Unstable
+public class ShuffleClientMetrics implements Updater {
 
   private MetricsRecord shuffleMetrics = null;
   private int numFailedFetches = 0;