[jira] [Commented] (HBASE-4027) Enable direct byte buffers LruBlockCache

["Li Pi (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-4027?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13064931#comment-13064931 ] 

Li Pi commented on HBASE-4027:
------------------------------

I have a copy based variant working right now, I'll submit the patch by the end of this week for that. Benchmarks show roughly 75% of the speed of the existing LruBlockCache, and around 4x the speed of FS cache reads. Realistically, we'll be using a two stage cache solution, with the LruBlockCache also holding some values, so for the majority of reads, it'll be the same speed as the LruBlockCache.

Currently pursueing a 0 copy solution - going to need to make everything run off ByteBuffers rather than byte[] though.

> Enable direct byte buffers LruBlockCache
> ----------------------------------------
>
>                 Key: HBASE-4027
>                 URL: https://issues.apache.org/jira/browse/HBASE-4027
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: Jason Rutherglen
>            Assignee: Li Pi
>            Priority: Minor
>
> Java offers the creation of direct byte buffers which are allocated outside of the heap.
> They need to be manually free'd, which can be accomplished using an documented {{clean}} method.
> The feature will be optional.  After implementing, we can benchmark for differences in speed and garbage collection observances.

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