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