svn merge -c 1442386 from trunk for HADOOP-9252. In StringUtils, humanReadableInt(..) has a race condition and the synchronization of limitDecimalTo2(double) can be avoided.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1442387 13f79535-47bb-0310-9956-ffa450edef68
merge YARN-360 from trunk. Allow apps to concurrently register tokens for renewal. Contributed by Daryn Sharp.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1442442 13f79535-47bb-0310-9956-ffa450edef68
HDFS-4404. Create file failure when the machine of first attempted NameNode is down. Contributed by Todd Lipcon.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1442462 13f79535-47bb-0310-9956-ffa450edef68