Apache Hadoop 2.6.4 Release Notes

These release notes cover new developer and user-facing incompatibilities, important issues, features, and major improvements.

Applications which made use of the LogAggregationContext in their application will need to revisit this code in order to make sure that their logs continue to get rolled out.

This fix includes public method interface change. A follow-up JIRA issue for this incompatibility for branch-2.7 is HADOOP-13579.