These release notes cover new developer and user-facing incompatibilities, important issues, features, and major improvements.
Work around for tmp file handling. sync() does not work as a result.
HDFS append() is disabled. It throws UnsupportedOperationException.
This patch changes the DatanodeProtocoal version number from 18 to 19. The patch allows NameNode to send both block replication and deletion request to a DataNode in response to a heartbeat.
This patch solves the null pointer exception issue in the 2 core tests TestFileOutputFormat and TestHarFileSystem in branch 19.
HADOOP-4943: Fixed fair share scheduler to utilize all slots when the task trackers are configured heterogeneously.
Fix the tasktracker for OOM exception by sharing the jobconf properties across tasks of the same job. Earlier a new instance was held for each task. With this fix, the job level configuration properties are shared across tasks of the same job.
Minor : HADOOP-3678 did not remove all the cases of spurious IOExceptions logged by DataNode.
Improve how RPC server reads and writes large buffers. Avoids soft-leak of direct buffers and excess copies in NIO layer.
fix memory leak of user/group information in fuse-dfs
libhdfs supports O_APPEND flag
Added a new conf property dfs.namenode.decommission.nodes.per.interval so that NameNode checks decommission status of x nodes for every y seconds, where x is the value of dfs.namenode.decommission.nodes.per.interval and y is the value of dfs.namenode.decommission.interval.