---->How region server will use heap and what are the
parameters will occupy heap memory
Region server heap memory consumption is mainly dependent on
below three.
- Block cache (Buffer maintained in heap for read)
- Memstore Size (Buffer maintained in heap for write and
flush)
- Other Objects created within region server while during
various operations.
Below two are the parameter which controls the max % of heap
block cache and block cache consume.
hfile.block.cache.size
hbase.regionserver.global.memstore.size
=>Below links will help in understading region server
configuration for block cache/memstore and region server sizing.
https://hbase.apache.org/book.html#perf.rs.memstore.size
https://hbase.apache.org/book.html#ops.capacity.regions.count
https://hbase.apache.org/book.html#block.cache.usage
-----> Is region server will use only 16 GB heap or even
other space of RAM
Region server will comsume maximum = 16GB of heap +
XX:MaxDirectMemorySize which you have configured.
MaxDirectMemorySize—The JVM has a kind of memory called
direct memory, which is distinct from normal JVM heap memory, that can run out.
You can increase the direct buffer memory either by increasing the maximum heap
size (see previous JVM Heap Size), which increases both the maximum heap and
the maximum direct memory, or by only increasing the maximum direct memory
using -XX:MaxDirectMemorySize. The following parameter added to the Java
application startup increases the maximum direct memory size to 256 megabytes:
