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https://issues.apache.org/jira/browse/CASSANDRA-6591?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13920032#comment-13920032
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Yuki Morishita edited comment on CASSANDRA-6591 at 3/5/14 1:21 AM:
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yeah, I did quick test and it looks like your patch can give what you want.
I think it is not exactly the same as one-(, five- or fifteen-)min rate of hit
rate, -though the error is negligible in this case-.
-so, +1.-
Edit: If Hits are not happening but Requests come in for a while, HitRate's 1-,
5- 15-min rates calculated like this goes way lower.
One solution would be to create our own EWMA which accepts update of type
double(hit rate) and update it for every request. How does this sound?
was (Author: yukim):
yeah, I did quick test and it looks like your patch can give what you want.
I think it is not exactly the same as one-(, five- or fifteen-)min rate of hit
rate, though the error is negligible in this case.
so, +1.
> un-deprecate cache recentHitRate and expose in o.a.c.metrics
> ------------------------------------------------------------
>
> Key: CASSANDRA-6591
> URL: https://issues.apache.org/jira/browse/CASSANDRA-6591
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Reporter: Chris Burroughs
> Assignee: Chris Burroughs
> Priority: Minor
> Attachments: j6591-1.2-v1.txt, j6591-1.2-v2.txt, j6591-1.2-v3.txt
>
>
> recentHitRate metrics were not added as part of CASSANDRA-4009 because there
> is not an obvious way to do it with the Metrics library. Instead hitRate was
> added as an all time measurement since node restart.
> This does allow changes in cache rate (aka production performance problems)
> to be detected. Ideally there would be 1/5/15 moving averages for the hit
> rate, but I'm not sure how to calculate that. Instead I propose updating
> recentHitRate on a fixed interval and exposing that as a Gauge.
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