remove spark2 codec

Author: turboFei

client-spark/spark-2/src/main/java/org/apache/spark/shuffle/celeborn/SparkUtils.java

@@ -42,7 +42,6 @@
 import org.apache.spark.SparkContext$;
 import org.apache.spark.TaskContext;
 import org.apache.spark.broadcast.Broadcast;
-import org.apache.spark.io.CompressionCodec;
 import org.apache.spark.scheduler.DAGScheduler;
 import org.apache.spark.scheduler.MapStatus;
 import org.apache.spark.scheduler.MapStatus$;
@@ -388,16 +387,14 @@ public static byte[] serializeGetReducerFileGroupResponse(
                     scala.reflect.ClassManifestFactory.fromClass(
                         GetReducerFileGroupResponse.class));
 
-            CompressionCodec codec = CompressionCodec.createCodec(sparkContext.conf());
             // Using `org.apache.commons.io.output.ByteArrayOutputStream` instead of the standard
             // one
             // This implementation doesn't reallocate the whole memory block but allocates
             // additional buffers. This way no buffers need to be garbage collected and
             // the contents don't have to be copied to the new buffer.
             org.apache.commons.io.output.ByteArrayOutputStream out =
                 new org.apache.commons.io.output.ByteArrayOutputStream();
-            try (ObjectOutputStream oos =
-                new ObjectOutputStream(codec.compressedOutputStream(out))) {
+            try (ObjectOutputStream oos = new ObjectOutputStream(out)) {
               oos.writeObject(broadcast);
             }
             byte[] _serializeResult = out.toByteArray();
@@ -426,10 +423,7 @@ public static GetReducerFileGroupResponse deserializeGetReducerFileGroupResponse
           GetReducerFileGroupResponse response = null;
 
           try {
-            CompressionCodec codec = CompressionCodec.createCodec(sparkContext.conf());
-            try (ObjectInputStream objIn =
-                new ObjectInputStream(
-                    codec.compressedInputStream(new ByteArrayInputStream(bytes)))) {
+            try (ObjectInputStream objIn = new ObjectInputStream(new ByteArrayInputStream(bytes))) {
               Broadcast<GetReducerFileGroupResponse> broadcast =
                   (Broadcast<GetReducerFileGroupResponse>) objIn.readObject();
               response = broadcast.value();