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https://issues.apache.org/jira/browse/CASSANDRA-11752?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15328269#comment-15328269
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Chris Lohfink commented on CASSANDRA-11752:
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for what its worth, if patching in ExponentiallyDecayingResvoir may want to
consider https://bitbucket.org/marshallpierce/hdrhistogram-metrics-reservoir
instead. the random sampling can lose 90th+ percentile pretty easily. If just
want trending its fine though.
> histograms/metrics in 2.2 do not appear recency biased
> ------------------------------------------------------
>
> Key: CASSANDRA-11752
> URL: https://issues.apache.org/jira/browse/CASSANDRA-11752
> Project: Cassandra
> Issue Type: Bug
> Components: Core
> Reporter: Chris Burroughs
> Assignee: Per Otterström
> Labels: metrics
> Attachments: boost-metrics.png, c-jconsole-comparison.png,
> c-metrics.png, default-histogram.png
>
>
> In addition to upgrading to metrics3, CASSANDRA-5657 switched to using a
> custom histogram implementation. After upgrading to Cassandra 2.2
> histograms/timer metrics are not suspiciously flat. To be useful for
> graphing and alerting metrics need to be biased towards recent events.
> I have attached images that I think illustrate this.
> * The first two are a comparison between latency observed by a C* 2.2 (us)
> cluster shoring very flat lines and a client (using metrics 2.2.0, ms)
> showing server performance problems. We can't rule out with total certainty
> that something else isn't the cause (that's why we measure from both the
> client & server) but they very rarely disagree.
> * The 3rd image compares jconsole viewing of metrics on a 2.2 and 2.1
> cluster over several minutes. Not a single digit changed on the 2.2 cluster.
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