HDFS-2788. svn merge -c 1231569 from trunk

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.23@1231570 13f79535-47bb-0310-9956-ffa450edef68

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -83,6 +83,8 @@ Release 0.23.1 - UNRELEASED
 
     HDFS-69. Improve the 'dfsadmin' commandline help. (harsh)
 
+    HDFS-2788. HdfsServerConstants#DN_KEEPALIVE_TIMEOUT is dead code (eli)
+
   OPTIMIZATIONS
 
     HDFS-2130. Switch default checksum to CRC32C. (todd)

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/common/HdfsServerConstants.java

@@ -86,7 +86,6 @@ public final class HdfsServerConstants {
   public static int READ_TIMEOUT_EXTENSION = 5 * 1000;
   public static int WRITE_TIMEOUT = 8 * 60 * 1000;
   public static int WRITE_TIMEOUT_EXTENSION = 5 * 1000; //for write pipeline
-  public static int DN_KEEPALIVE_TIMEOUT = 5 * 1000;
 
   /**
    * Defines the NameNode role.