YARN-2204. TestAMRestart#testAMRestartWithExistingContainers assumes CapacityScheduler. (Robert Kanter via kasha)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1605550 13f79535-47bb-0310-9956-ffa450edef68
svn merge -c 1605565 from trunk for HDFS-6595. Allow the maximum threads for balancing on datanodes to be configurable.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1605566 13f79535-47bb-0310-9956-ffa450edef68