MAPREDUCE-5251. Reducer should not implicate map attempt if it has insufficient space to fetch map output. Contributed by Ashwin Shankar


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.23@1507384 13f79535-47bb-0310-9956-ffa450edef68
MAPREDUCE-1981. Improve getSplits performance by using listLocatedStatus. Contributed by Hairong Kuang and Jason Lowe


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.23@1507388 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/branch-0.23' into branch-0.23-gd