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From "Robert Joseph Evans (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (MAPREDUCE-2494) Make the distributed cache delete entires using LRU priority
Date Mon, 16 May 2011 19:40:47 GMT

     [ https://issues.apache.org/jira/browse/MAPREDUCE-2494?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Robert Joseph Evans updated MAPREDUCE-2494:
-------------------------------------------

    Attachment: MAPREDUCE-2494-V1.patch

First patch, uses LinkedHashMap to keep track of LRU ordering of cachedArchives, so that removal
of them can happen in an orderly manor.

> Make the distributed cache delete entires using LRU priority
> ------------------------------------------------------------
>
>                 Key: MAPREDUCE-2494
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-2494
>             Project: Hadoop Map/Reduce
>          Issue Type: Improvement
>          Components: distributed-cache
>    Affects Versions: 0.21.0
>            Reporter: Robert Joseph Evans
>            Assignee: Robert Joseph Evans
>         Attachments: MAPREDUCE-2494-V1.patch
>
>
> Currently the distributed cache will wait until a cache directory is above a preconfigured
threshold.  At which point it will delete all entries that are not currently being used. 
It seems like we would get far fewer cache misses if we kept some of them around, even when
they are not being used.  We should add in a configurable percentage for a goal of how much
of the cache should remain clear when not in use, and select objects to delete based off of
how recently they were used, and possibly also how large they are/how difficult is it to download
them again.

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