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From "Andrew Purtell (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HBASE-14757) Reduce allocation pressure imposed by block encoding
Date Wed, 04 Nov 2015 03:05:27 GMT
Andrew Purtell created HBASE-14757:
--------------------------------------

             Summary: Reduce allocation pressure imposed by block encoding
                 Key: HBASE-14757
                 URL: https://issues.apache.org/jira/browse/HBASE-14757
             Project: HBase
          Issue Type: Improvement
            Reporter: Andrew Purtell
            Assignee: Andrew Purtell
             Fix For: 2.0.0, 1.2.0, 1.3.0, 0.98.17


Using Flight Recorder to look at the object allocation profiles of regionservers processing
the various YCSB workloads when block encoding is enabled (specifically, FAST_DIFF, but this
applies to any), we can see:
- Allocations of byte[] for block encoding contribute 40-70% of all allocation pressure in
TLABs. 
- Of that subset of allocation pressure, ~50-70% is byte[] for SeekerState
- Greater than 99% of allocation of byte[] outside of TLABs are for read buffers for HFileBlock#readBlockDataInternal.

This issue is for investigation of strategy for and impact of reducing that allocation pressure.
Reducing allocation pressure reduces demand for GC, which reduces GC activity overall, which
reduces a source of system latency.



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