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  1. Cassandra
  2. CASSANDRA-11752

histograms/metrics in 2.2 do not appear recency biased

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    Details

    • Severity:
      Normal

      Description

      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.

        Attachments

        1. 11752-2.2.txt
          41 kB
          Per Otterström
        2. 11752-2.2-v2.txt
          43 kB
          Per Otterström
        3. 11752-2.2-v2b.txt
          2 kB
          Per Otterström
        4. boost-metrics.png
          152 kB
          Chris Burroughs
        5. c-jconsole-comparison.png
          142 kB
          Chris Burroughs
        6. c-metrics.png
          78 kB
          Chris Burroughs
        7. default-histogram.png
          31 kB
          Chris Burroughs
        8. server-patch-v2.png
          35 kB
          Per Otterström

          Activity

            People

            • Assignee:
              eperott Per Otterström
              Reporter:
              cburroughs Chris Burroughs
              Authors:
              Per Otterström
              Reviewers:
              T Jake Luciani
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              Dates

              • Created:
                Updated:
                Resolved: