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https://issues.apache.org/jira/browse/HBASE-18652?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16163227#comment-16163227
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stack commented on HBASE-18652:
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[~biju74] Thank you for working on this. Patch looks good. The approach is to
add new counters for L1 and L2 and then there will be the aggregated counter
also, the one that currently exists? When you look at L1 in the UI in the L1
panel, it reports stats. These are the aggregated hits not those for the L1
cache only? Ditto for the L2? If you look at the L2 panel, it is again showing
the aggregated hits, not just those for L2?
One concern adding two new counters is that we already doing lots of counting
(counting consumes massive amounts of CPU). Would subtracting L1 hits from
global hits work for L2 hit count?
On adding synchronize on the get of L1, how often are we calling the getL1?
Everytime we want to update counters or just at startup? Thanks.
> Expose individual cache stats in a CombinedCache through JMX
> ------------------------------------------------------------
>
> Key: HBASE-18652
> URL: https://issues.apache.org/jira/browse/HBASE-18652
> Project: HBase
> Issue Type: Improvement
> Components: regionserver
> Reporter: Biju Nair
> Assignee: Biju Nair
> Fix For: 1.4.0, 1.5.0, 2.0.0-alpha-3
>
> Attachments: 18652-branch-1-V3.0.PATCH, HBASE-18652-addendum.patch,
> HBASE-18652-BRANCH-1.PATCH, HBASE-18652-branch-1-v1.0.patch,
> HBASE-18652-branch-1-V2.0.PATCH, HBASE-18652-branch-1-V3.0.PATCH,
> HBASE-18652.PATCH, HBASE-18652-V1.0.PATCH, HBASE-18652-V2.0.PATCH,
> HBASE-18652-WIP.PATCH
>
>
> With offHeap cache being used to store data blocks and on-heap for index and
> bloom filters, exposing the stats from the individual caches through JMX will
> help understand the cache usage trend. Currently the combined cache stats is
> available through JMX which may not provide insight into the individual cache
> usage.
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