YARN-538. RM address DNS lookup can cause unnecessary slowness on every JHS page load. (sandyr via tucu)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1464198 13f79535-47bb-0310-9956-ffa450edef68
YARN-458. YARN daemon addresses must be placed in many different configs. (sandyr via tucu)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1464205 13f79535-47bb-0310-9956-ffa450edef68
HADOOP-9401. CodecPool: Add counters for number of (de)compressors leased out. (kkambatl via tucu)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1464220 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/branch-2' into branch-2-gd
Merge remote branch 'origin/branch-2-gd' into fb-MAPREDUCE-4884-branch-2-gd