YARN-1408 Preemption caused Invalid State Event: ACQUIRED at KILLED and caused a task timeout for 30mins. (Sunil G via mayank)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1610860 13f79535-47bb-0310-9956-ffa450edef68
HADOOP-7664. Move attribution to release 2.6.0 section in CHANGES.txt.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1610873 13f79535-47bb-0310-9956-ffa450edef68
YARN-2233. Implemented ResourceManager web-services to create, renew and cancel delegation tokens. Contributed by Varun Vasudev.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1610876 13f79535-47bb-0310-9956-ffa450edef68
HADOOP-10673. Update rpc metrics when the call throws an exception. Contributed by Ming Ma.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1610879 13f79535-47bb-0310-9956-ffa450edef68