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https://issues.apache.org/jira/browse/HBASE-11331?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14107368#comment-14107368
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Nick Dimiduk commented on HBASE-11331:
--------------------------------------
As best as I can tell, both of these configurations stay entirely in
BlockCache. Verified by looking at the RS BlockCache stats and confirmed by the
low iowait stat being basically flat for them both. Looks like enabling this
feature when it's not needed is quite expensive.
|| ||=false, 11g||=true, 40g||delta|
|hbase.regionserver.server.Get_num_ops|15.15 k|6.07 k|{color:red}-60%{color}|
|hbase.regionserver.server.Get_mean|0.00 ns| 0.00 ns|{color:green}0%{color}|
|hbase.regionserver.server.Get_99th_percentile|1.00 ms|22.65
ms|{color:red}2165%{color}|
|hbase.regionserver.jvmmetrics.GcTimeMillis|48.89 ms|441.33
ms|{color:red}802%{color}|
|proc.loadavg.1min|0.56|3.25|{color:red}480%{color}|
|proc.stat.cpu.percpu{type=iowait}|3.55|3.47|{color:green}-2%{color}|
|hbase.regionserver.server.blockCacheCount|181.75 k|666.44
k|{color:green}266%{color}|
> [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-11331.03.patch, HBASE-11331.04.patch,
> HBASE-11331.05.patch, HBASE-11331LazyBlockDecompressperfcompare.pdf,
> lazy-decompress.02.0.pdf, lazy-decompress.02.1.json,
> lazy-decompress.02.1.pdf, v03-20g-045g-false.pdf, v03-20g-045g-true-16h.pdf,
> v03-20g-045g-true.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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