These release notes cover new developer and user-facing incompatibilities, important issues, features, and major improvements.
Fix a bug with HDFS file close() mistakenly introduced by HADOOP-3681.
NameNode keeps a count of number of blocks scheduled to be written to a datanode and uses it to avoid allocating more blocks than a datanode can hold.
Avoid spurious exceptions logged at DataNode when clients read from DFS.
Allows the user to change the maximum number of xceivers in the datanode.