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From Per Otterström (JIRA) <j...@apache.org>
Subject [jira] [Updated] (CASSANDRA-11752) histograms/metrics in 2.2 do not appear recency biased
Date Tue, 30 Aug 2016 06:30:22 GMT

     [ https://issues.apache.org/jira/browse/CASSANDRA-11752?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Per Otterström updated CASSANDRA-11752:
---------------------------------------
    Attachment: 11752-2.2-v2b.txt

Fixing double division and rounding.

> 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
>             Fix For: 2.2.8, 3.0.9, 3.8
>
>         Attachments: 11752-2.2-v2.txt, 11752-2.2-v2b.txt, 11752-2.2.txt, boost-metrics.png,
c-jconsole-comparison.png, c-metrics.png, default-histogram.png, server-patch-v2.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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