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From "stack (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-11520) Simplify offheap cache config by removing the confusing "hbase.bucketcache.percentage.in.combinedcache"
Date Wed, 16 Jul 2014 00:27:04 GMT

    [ https://issues.apache.org/jira/browse/HBASE-11520?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14062926#comment-14062926
] 

stack commented on HBASE-11520:
-------------------------------

Nice review.

Thank you for prompting the refactor.  It was hard to grok as it was.  It is a bit cleaner
now (could be refactored more but will leave as is else will start to ripple afar).

On the test, offheap plus BUCKET_CACHE_COMBINED_KEY == false is a legit set up.  This is how
you ask for an L1+L2 that is not 'combined'.  The L2 gets registered as the victimHandler
for L1.  When eviction thread runs, blocks moved to L2.  When we search for blocks, we'll
look in both places (first in LruBC then in its victim if not present...).  Given this latter,
the package-info as it is in the patch is right by my reckoning.  From LruBlockCache:

{code}
  public Cacheable getBlock(BlockCacheKey cacheKey, boolean caching, boolean repeat,
      boolean updateCacheMetrics) {
    LruCachedBlock cb = map.get(cacheKey);
    if (cb == null) {
      if (!repeat && updateCacheMetrics) stats.miss(caching);
      if (victimHandler != null) {
        return victimHandler.getBlock(cacheKey, caching, repeat, updateCacheMetrics);
      }
      return null;
    }
    if (updateCacheMetrics) stats.hit(caching);
    cb.access(count.incrementAndGet());
    return cb.getBuffer();
  }
{code}



> Simplify offheap cache config by removing the confusing "hbase.bucketcache.percentage.in.combinedcache"
> -------------------------------------------------------------------------------------------------------
>
>                 Key: HBASE-11520
>                 URL: https://issues.apache.org/jira/browse/HBASE-11520
>             Project: HBase
>          Issue Type: Sub-task
>          Components: io
>    Affects Versions: 0.99.0
>            Reporter: stack
>            Assignee: stack
>             Fix For: 0.99.0, 2.0.0
>
>         Attachments: 11520.txt, 11520v2.txt
>
>
> Remove "hbase.bucketcache.percentage.in.combinedcache".  It is unnecessary complication
of block cache config.  Let L1 config setup be as it is whether a L2 present or not, just
set hfile.block.cache.size (not hbase.bucketcache.size * (1.0 - hbase.bucketcache.percentage.in.combinedcache)).
 For L2, let hbase.bucketcache.size be the actual size of the bucket cache, not hbase.bucketcache.size
* hbase.bucketcache.percentage.in.combinedcache.
> Attached patch removes the config. and updates docs.  Adds tests to confirm configs are
as expected whether a CombinedBlockCache deploy or a strict L1+L2 deploy.



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