Now, all sub-tasks has been resolved now (except the HBASE-21946 because of the hadoop dependency problem), will provide some performance benckmarks to show the latency improvement.
Optimize the MultiByteBuff#get(ByteBuffer, offset, len)
Balance shell command broken in HBase-3.0.0
The default 8KB buffer in requestFileDescriptors#BufferedOutputStream is causing lots of heap allocation in HBase when using short-circut read
When evictableMmapped or evictable size is zero, do not throw NoSuchElementException
[book] dfs.client.read.shortcircuit is referenced as hbase-site.xml config and not described in section 7