YARN-596. Use scheduling policies throughout the queue hierarchy to decide which containers to preempt (Wei Yan via Sandy Ryza)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1598197 13f79535-47bb-0310-9956-ffa450edef68
MAPREDUCE-5895. Close streams properly to avoid leakage in TaskLog. Contributed by Kousuke Saruta.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1598209 13f79535-47bb-0310-9956-ffa450edef68