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From "Jonathan Gray (JIRA)" <j...@apache.org>
Subject [jira] Updated: (HBASE-1460) Concurrent LRU Block Cache
Date Fri, 26 Jun 2009 20:51:47 GMT

     [ https://issues.apache.org/jira/browse/HBASE-1460?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Jonathan Gray updated HBASE-1460:
---------------------------------

    Attachment: HBASE-1460-v4.patch

Cleans up some of the code.

Adds two more tests, one which very fully tests eviction of all three priorities.  The other
is to test "scan resistance" and also that balanced eviction happens across multiple buckets.

I changed the detailed constructor from taking the actual sizes of the different things, to
taking float factors.  Those factors are stored in the class so everything is fully dynamic.

> 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, HBASE-1460-v2.patch, HBASE-1460-v3.patch, HBASE-1460-v4.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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