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https://issues.apache.org/jira/browse/HBASE-4018?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13053486#comment-13053486
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Jonathan Gray commented on HBASE-4018:
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bq. Optimal solution would be building a slab allocated block cache within
java. Use reference counting for a zero copy solution. This is difficult to
implement and debug though.
I'm working on this. I think implementing both directions is worthwhile and we
can run good comparisons (including against linux fs cache + local datanodes).
bq. It would seem best to move in the direction of local HDFS file access and
allow plugging in the block cache as a point of comparison / legacy.
I think it's best to move in all directions and do comparisons. I've already
seen performance differences between fs cache and the actual hbase block cache.
There's also compressed vs. decompressed (fs cache will always be compressed)
> Attach memcached as secondary block cache to regionserver
> ---------------------------------------------------------
>
> Key: HBASE-4018
> URL: https://issues.apache.org/jira/browse/HBASE-4018
> Project: HBase
> Issue Type: Improvement
> Components: regionserver
> Reporter: Li Pi
> Assignee: Li Pi
>
> Currently, block caches are limited by heap size, which is limited by garbage
> collection times in Java.
> We can get around this by using memcached w/JNI as a secondary block cache.
> This should be faster than the linux file system's caching, and allow us to
> very quickly gain access to a high quality slab allocated cache.
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