HDFS-4739. NN can miscalculate the number of extra edit log segments to retain. Contributed by Aaron T. Myers.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1471769 13f79535-47bb-0310-9956-ffa450edef68
MAPREDUCE-5166. Fix ConcurrentModificationException due to insufficient synchronization on updates to task Counters. Contributed by Sandy Ryza.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1471796 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/trunk' into trunk-gd
Merge remote branch 'origin/trunk-gd' into fb-HDFS-4312-trunk-gd