HDFS-6194. Merge r1587660 from trunk

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1587665 13f79535-47bb-0310-9956-ffa450edef68
YARN-1892. Improved some logs in the scheduler. Contributed by Jian He.
svn merge --ignore-ancestry -c 1587717 ../../trunk/


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1587718 13f79535-47bb-0310-9956-ffa450edef68
MAPREDUCE-5836. Fix typo in RandomTextWriter (Akira AJISAKA via jeagles)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1587722 13f79535-47bb-0310-9956-ffa450edef68