HBASE-21879 Read HFile ’s Block into ByteBuffer directly. 1. Background For reducing the Java GC impact to p99/p999 RPC latency, HBase 2.x has made an offheap read and write path. The KV are allocated didn’t accomplish this before because HDFS does not support the ByteBuffer pread interface, also because of its complexity. For the ByteBuffer pread, we have issue ​HDFS-3246​ to track this, so further HDFS can also be easy as the 3.1 part described. 3.3 Make downstream API can accept ByteBuff or ByteBuffer as arguments The first obstacle when implementing the block off-heap reading is: many downstream

java.nio.ByteBuffer, etc.) and is what all codecs work on. See Data Buffers and Codecs in the "Spring Core" section for more on this topic. The spring-core module provides byte[], ByteBuffer, DataBuffer and metadata values. By default only the basic codecs from spring-core for String, byte[], and ByteBuffer are registered. Adding spring-web provides access to more that can be registered as follows:

provided scope to avoid compile warnings. 435 Chapter 8. Data Buffers and Codecs Java NIO provides ByteBuffer but many libraries build their own byte buffer API on top, especially for network operations where implementations of DataBuffer can grow and shrink on demand. 2. Wrap an existing byte[] or java.nio.ByteBuffer, which decorates the given data with a DataBuffer implementation and that does not involve allocation y for others. 8.2. DataBuffer The DataBuffer interface offers similar operations as java.nio.ByteBuffer but also brings a few additional benefits some of which are inspired by the Netty ByteBuf. Below

and metadata values. By default only the basic codecs from spring-core for String, byte[], and ByteBuffer are registered. Adding spring-web provides access to more that can be registered as follows: