HDFS-3941. Backport HDFS-3498 and HDFS-3601: Support replica removal in BlockPlacementPolicy and make BlockPlacementPolicyDefault extensible for reusing code in subclasses, and add BlockPlacementPolicyWithNodeGroup to support block placement with 4-layer network topology.  Contributed by Junping Du and Jing Zhao


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-1@1410690 13f79535-47bb-0310-9956-ffa450edef68
HDFS-4105. The SPNEGO user for secondary namenode should use the web keytab. Contributed by Arpit Gupta.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-1@1410693 13f79535-47bb-0310-9956-ffa450edef68
HADOOP-9036. Fix racy test case TestSinkQueue (Backport HADOOP-7292). Backported by Suresh Srinivas.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-1@1410992 13f79535-47bb-0310-9956-ffa450edef68
modify conf
MAPREDUCE-4792. Unit Test TestJobTrackerRestartWithLostTracker fails with ant-1.8.4. Contributed by Amir Sanjar.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-1@1411073 13f79535-47bb-0310-9956-ffa450edef68
fixed CHANGES.txt to correctly show five patches applied in release 1.1.1 instead of release 1.2.0.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-1@1411102 13f79535-47bb-0310-9956-ffa450edef68
HDFS-4208. NameNode could be stuck in SafeMode due to never-created blocks. Contributed by Brandon Li.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-1@1412218 13f79535-47bb-0310-9956-ffa450edef68
HDFS-4207. All hadoop fs operations fail if the default fs is down even if a different fs is specified in the command. Contributed by Jing Zhao.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-1@1412229 13f79535-47bb-0310-9956-ffa450edef68
HDFS-4219. Backport slive to branch-1. Backported by Arpit Gupta.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-1@1413767 13f79535-47bb-0310-9956-ffa450edef68
HDFS-4208. Reverting change r1412218 which committed the wrong version of the patch.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-1@1413887 13f79535-47bb-0310-9956-ffa450edef68
HADOOP-9095. Backport HADOOP-8372: NetUtils.normalizeHostName() incorrectly handles hostname starting with a numeric character.  Contributed by Jing Zhao 


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-1@1413969 13f79535-47bb-0310-9956-ffa450edef68
HDFS-4208. NameNode could be stuck in SafeMode due to never-created blocks. Contributed by Brandon Li.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-1@1413981 13f79535-47bb-0310-9956-ffa450edef68
HADOOP-9099. TestNetUtils fails if "UnknownHost" is resolved as a valid hostname.  Contributed by Ivan Mitic 


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-1@1414483 13f79535-47bb-0310-9956-ffa450edef68
MAPREDUCE-4778. Fair scheduler event log is only written if directory exists on HDFS. Contributed by Sandy Ryza.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-1@1414731 13f79535-47bb-0310-9956-ffa450edef68
use thead pool insteadn of individule daemon thread for dataXreceiver related work
fix balancer
improve RPC read throughput
revert to auto config for RPC reader
fix some perm issue
pooling rpc read threads