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https://issues.apache.org/jira/browse/HBASE-11323?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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stack resolved HBASE-11323.
---------------------------
Resolution: Fixed
Release Note: Use the LruBlockCache default if your data fits the
blockcache. If block cache churn or you want a block cache that is immune to
the vagaries of BC, deploy the offheap bucketcache. See
http://people.apache.org/~stack/bc/
> BucketCache all the time!
> -------------------------
>
> Key: HBASE-11323
> URL: https://issues.apache.org/jira/browse/HBASE-11323
> Project: HBase
> Issue Type: Sub-task
> Components: io
> Reporter: stack
> Assignee: stack
> Fix For: 2.0.0
>
> Attachments:
> BlockCacheReportLruBlockCachevsOffHeapCombinedBlockCacheSmall4G (1).pdf,
> ReportBlockCache.pdf
>
>
> One way to realize the parent issue is to just enable bucket cache all the
> time; i.e. always have offheap enabled. Would have to do some work to make
> it drop-dead simple on initial setup (I think it doable).
> So, upside would be the offheap upsides (less GC, less likely to go away and
> never come back because of full GC when heap is large, etc.).
> Downside is higher latency. In Nick's BlockCache 101 there is little to no
> difference between onheap and offheap. In a basic compare doing scans and
> gets -- details to follow -- I have BucketCache deploy about 20% less ops
> than LRUBC when all incache and maybe 10% less ops when falling out of cache.
> I can't tell difference in means and 95th and 99th are roughly same (more
> stable with BucketCache). GC profile is much better with BucketCache -- way
> less. BucketCache uses about 7% more user CPU.
> More detail on comparison to follow.
> I think the numbers disagree enough we should probably do the [~lhofhansl]
> suggestion, that we allow you to have a table sit in LRUBC, something the
> current bucket cache layout does not do.
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