svn merge -c 1482658 from trunk for HDFS-4813. Add volatile to BlocksMap.blocks so that the replication thread can see the updated value.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1482659 13f79535-47bb-0310-9956-ffa450edef68
svn merge -c 1482661 from trunk for HDFS-3180. Add socket timeouts to WebHdfsFileSystem.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1482662 13f79535-47bb-0310-9956-ffa450edef68