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https://issues.apache.org/jira/browse/MAPREDUCE-2494?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13033113#comment-13033113
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Robert Joseph Evans commented on MAPREDUCE-2494:
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I agree completely. The 10 min is already configurable, sort of. It should
also be very simple to add it in. The hardest part will probably be updating
the tests. I figure I will make the reference count inc/dec in the CacheStatus
methods, and then if the reference count ever goes to 0 we update a timestamp
to indicate when it was last used, so we can purge oldest objects first.
> 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
>
> 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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