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From "stack (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HBASE-1460) Concurrent LRU Block Cache
Date Mon, 01 Jun 2009 00:25:07 GMT

    [ https://issues.apache.org/jira/browse/HBASE-1460?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12714945#action_12714945
] 

stack commented on HBASE-1460:
------------------------------

I think the bulk of the '30/May/09 05:43 PM' comment should go into class comment or into
the hfile package-info javadoc.  Its good stuff on implementation.  Belongs in code rather
than buried here in JIRA.

I wonder if the eviction thread will be able to keep up?  We can test and see.

> Concurrent LRU Block Cache
> --------------------------
>
>                 Key: HBASE-1460
>                 URL: https://issues.apache.org/jira/browse/HBASE-1460
>             Project: Hadoop HBase
>          Issue Type: Improvement
>          Components: io
>            Reporter: Jonathan Gray
>            Assignee: Jonathan Gray
>             Fix For: 0.20.0
>
>         Attachments: HBASE-1460-v1.patch
>
>
> The LRU-based block cache that will be committed in HBASE-1192 is thread-safe but contains
a big lock on the hash map.  Under high load, the block cache will be hit very heavily from
a number of threads, so it needs to be built to handle massive concurrency.
> This issue aims to implement a new block cache with LRU eviction, but backed by a ConcurrentHashMap
and a separate eviction thread.  Influence will be drawn from Solr's ConcurrentLRUCache, however
there are major differences because solr treats all cached elements as equal size whereas
we are dependent on our HeapSize interface with realistic (though approximate) heap usage.

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