Make the distributed cache delete entires using LRU priority
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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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