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Date: Fri, 15 Aug 2014 21:59:20 +0000 (UTC)
From: "Nick Dimiduk (JIRA)" <jira@apache.org>
To: issues@hbase.apache.org
Message-ID: <JIRA.12728433.1405864289714.11830.1408139960193@arcas>
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References: <JIRA.12728433.1405864289714@arcas>
Subject: [jira] [Commented] (HBASE-11550) Custom value for
 BUCKET_CACHE_BUCKETS_KEY should be sorted
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    [ https://issues.apache.org/jira/browse/HBASE-11550?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14099232#comment-14099232 ] 

Nick Dimiduk commented on HBASE-11550:
--------------------------------------

[~stack] Trivial is fine. I think it's important that the semantics of the allocator placement policy be identical, but the change itself is trivial. I didn't communicate my shift in opinion after researching allocation strategies. I believe Ted's point about roundUpToBucketSizeInfo is quite valid, makes it clear that this allocator implementation does indeed depend on the order of target sizes.

I don't think it fair to the new contributor to have their contributions get caught up in the project politicking. I'm happy to help see a valuable patch through, even if the circumstances around it are not ideal.

More, valid tests are better than less. I don't know what the new issue's test might look like. For a cache of configured size and shape, for given sequence of blocks, they're placed such that they all fit, something like this? I'm much more interested in thinking through what constitutes a "better" or "worse" criteria for HBase and if there's a different allocation strategy that fits HBase access patterns "better".

This looks like a decent starting point http://www.memorymanagement.org/mmref/index.html

> Custom value for BUCKET_CACHE_BUCKETS_KEY should be sorted
> ----------------------------------------------------------
>
>                 Key: HBASE-11550
>                 URL: https://issues.apache.org/jira/browse/HBASE-11550
>             Project: HBase
>          Issue Type: Bug
>    Affects Versions: 0.99.0, 0.98.4, 0.98.5
>            Reporter: Ted Yu
>            Assignee: Gustavo Anatoly
>            Priority: Trivial
>             Fix For: 0.99.0, 2.0.0, 0.98.6
>
>         Attachments: HBASE-11550-v1.patch, HBASE-11550-v2.patch, HBASE-11550-v3.patch, HBASE-11550-v4-0.98.patch, HBASE-11550-v4.patch, HBASE-11550.patch
>
>
> User can pass bucket sizes through "hbase.bucketcache.bucket.sizes" config entry.
> The sizes are supposed to be in increasing order. Validation should be added in CacheConfig#getL2().


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