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From "Nick Dimiduk (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HBASE-11331) [blockcache] lazy block decompression
Date Sat, 02 Aug 2014 00:25:40 GMT

     [ https://issues.apache.org/jira/browse/HBASE-11331?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Nick Dimiduk updated HBASE-11331:
---------------------------------

    Attachment: HBASE-11331.02.patch

Thanks [~stack]. v02 addresses the exception you see here. It also:
 - makes the feature configurable. enable with {{hbase.block.data.cachecompressed=true}}
 - only retains data blocks in their "packed" format in memory. Everything else *should* be
cached decompressed.

One observation: when running the RS with a compression-enabled table, I see a lot of log
messages says "got brand-new decompressor". I don't see any messages saying "got recycled
compressor" (i've enabled debug logging for org.apache.hadoop.io.compress). I think we're
not returning the objects to the pool. Running this small PE workload results in ~1600 said
log lines. Run the same workload with hbase.block.data.cachecompressed=true, I see ~10k, so
this will have a significant impact on the performance of this feature. Will investigate further.

> [blockcache] lazy block decompression
> -------------------------------------
>
>                 Key: HBASE-11331
>                 URL: https://issues.apache.org/jira/browse/HBASE-11331
>             Project: HBase
>          Issue Type: Improvement
>          Components: regionserver
>            Reporter: Nick Dimiduk
>            Assignee: Nick Dimiduk
>         Attachments: HBASE-11331.00.patch, HBASE-11331.01.patch, HBASE-11331.02.patch,
HBASE-11331LazyBlockDecompressperfcompare.pdf
>
>
> Maintaining data in its compressed form in the block cache will greatly increase our
effective blockcache size and should show a meaning improvement in cache hit rates in well
designed applications. The idea here is to lazily decompress/decrypt blocks when they're consumed,
rather than as soon as they're pulled off of disk.
> This is related to but less invasive than HBASE-8894.



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