[jira] [Commented] (HBASE-11323) BucketCache all the time!

["Hudson (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-11323?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14107881#comment-14107881 ] 

Hudson commented on HBASE-11323:
--------------------------------

SUCCESS: Integrated in HBase-0.94-security #514 (See [https://builds.apache.org/job/HBase-0.94-security/514/])
HBASE-11323 Add MultiRowMutation tests. (Liu Shaohui) (larsh: rev 44492624d4b8a6cf1ce1c7ba595f3a3447f9f536)
* src/test/java/org/apache/hadoop/hbase/coprocessor/TestMultiRowMutationProtocol.java


> 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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