HADOOP-10337 ConcurrentModificationException from MetricsDynamicMBeanBase.createMBeanInfo() (Liang Xie via stack)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1576189 13f79535-47bb-0310-9956-ffa450edef68
HDFS-6085. Improve CacheReplicationMonitor log messages a bit (cmccabe)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1576195 13f79535-47bb-0310-9956-ffa450edef68