The related JIRAs are HDFS-3577, HDFS-3318, and HDFS-3788. Backporting them can fix some WebHDFS performance issues in branch-1.
WebHDFS hits a Jetty performance issue
Hftp hangs on transfers >2GB
WebHdfsFileSystem can not read files larger than 24KB
distcp can't copy large files using webhdfs due to missing Content-Length header