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From "stack (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-11307) Deprecate SlabCache
Date Sat, 07 Jun 2014 03:09:01 GMT

    [ https://issues.apache.org/jira/browse/HBASE-11307?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14020669#comment-14020669

stack commented on HBASE-11307:

>From [~zjushch] in description for HBASE-7404: 

{quote}We have studied and test SlabCache first, but the result is bad, because:
 SlabCache use SingleSizeCache, its use ratio of memory is low because kinds of block size,
especially using DataBlockEncoding
 SlabCache is uesd in DoubleBlockCache, block is cached both in SlabCache and LruBlockCache,
put the block to LruBlockCache again if hit SlabCache , it causes CMS and heap fragment don't
get any better{quote}

The patch in HBASE-4089 has work to dump stats on slabcache and bucketcache and graphically
illustrates difference in their sophistication.  I was sort of hoping for some perf numbers
definitively showing it worse before moving to purge it but its hard to do (so many combinations
to try!).

So I'm for just making a call. Intellectually we can see the its deploy type using DoubleBlockCache
is not going to be as good as CombinedBlockCache for GC and it will take a bunch of work,
that no one of us has done nor is likely to do, trying SlabCache in different deploy scenarios;
e.g. use SlabCache in CombinedBlockCache deploy.

So, in the name of simplification and being able to narrow our limited attention span, at
first I was thinking just talk down SlabCache but better/cleaner, lets just call it a stepping
stone and just remove it altogether.  +1 on patch.  Needs to include hardening of the just-added
doc in refguide which discourages SlabCache to instead do violent discouragement (noting gone
in 1.0).

> Deprecate SlabCache
> -------------------
>                 Key: HBASE-11307
>                 URL: https://issues.apache.org/jira/browse/HBASE-11307
>             Project: HBase
>          Issue Type: Sub-task
>          Components: regionserver
>            Reporter: Nick Dimiduk
>            Assignee: Nick Dimiduk
>             Fix For: 0.99.0
>         Attachments: HBASE-11307.00.patch
> BucketCache is more feature-full than SlabCache. My performance testing indicates that
SlabCache doesn't perform well as memory footprint grows. I believe BucketCache is seeing
more production usage than SlabCache at this point. I suggest we consolidate on BucketCache.

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