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From "Chris Lohfink (JIRA)" <>
Subject [jira] [Commented] (CASSANDRA-12848) Nodetool proxyhistograms/cfhistograms still report latency as flat result
Date Tue, 27 Feb 2018 22:00:00 GMT


Chris Lohfink commented on CASSANDRA-12848:

The buckets for the EH go in 20% jumps, so everything in a bucket from 700-840 for example
will be reported as "840". This means that it will round up to nearest 20% and all the variance
within the 20% is lost. 2.1 was lossy (randomly threw away latency recordings regardless of
how important they are) but 2.2+ has a 20% error threshold (will in worse case report as 20%
worse, not better)

> Nodetool proxyhistograms/cfhistograms still report latency as flat result
> -------------------------------------------------------------------------
>                 Key: CASSANDRA-12848
>                 URL:
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>            Reporter: Nutchanon Leelapornudom
>            Priority: Major
>              Labels: metrics
>         Attachments: clientrequest-latency.png, image001.png
> Even patched in CASSANDRA-11752, nodetool proxyhistograms/cfhistograms(2.2)/tablehistograms(3.0,3.x)
still report read/write latency as flat result. That cause Cassandra metric org.apache.cassandra.metrics.ClientRequest.Read/Write.Latency.xxpercentile
report incorrect pattern.
> I have attached the result which I tested on cassandra 3.0.9. It indicate read latency
as flat line whereas read count has a movement normally.

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