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From "Mikhail Stepura (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-6423) Some histogram metrics of long[] type are unusable with Graphite
Date Fri, 29 Nov 2013 22:02:35 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-6423?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13835552#comment-13835552
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Mikhail Stepura commented on CASSANDRA-6423:
--------------------------------------------

https://github.com/codahale/metrics/issues is a good place to start this discussion.
At the moment GraphiteReporter doesn't handle Gauges which return an array (which is perfectly
valid use case) instead of a single value.
I think checking {{object.getClass().isArray()}} and using {{Arrays.toString(object)}} should
help

> Some histogram metrics of long[] type are unusable with Graphite
> ----------------------------------------------------------------
>
>                 Key: CASSANDRA-6423
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-6423
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>         Environment: Cassandra 2.0.3, Oracle Linux 6.3, graphite
>            Reporter: Nikolai Grigoriev
>            Priority: Minor
>
> I am not entirely sure if this is a Cassandra issue or the limitation of the graphite
reporter agent. But since the metrics in question are created by Cassandra itself I have decided
that it may be appropriate to report it here.
> I am using Graphite with Cassandra 2.0.x and I have recently noticed frequent 'invalid
line' messages in Graphite log. Unfortunately Graphite did not provide enough details so I
hacked it a bit to get more verbose error message with the metric name. And here is what I
have found:
> {code}
> 29/11/2013 16:07:16 :: invalid line ".org.apache.cassandra.metrics.ColumnFamily.mykeyspace.some_cf.EstimatedRowSizeHistogram.value
[J@17c26ba5 1385741236"received from client 192.168.20.157:55553, ignoring
> 29/11/2013 16:07:16 :: invalid line ".org.apache.cassandra.metrics.ColumnFamily.mykeyspace.some_cf.EstimatedColumnCountHistogram.value
[J@5d2929d2 1385741236"received from client 192.168.20.157:55553, ignoring
> 29/11/2013 16:07:16 :: invalid line ".org.apache.cassandra.metrics.ColumnFamily.mykeyspace.some_cf.EstimatedRowSizeHistogram.value
[J@3978c9c6 1385741236"received from client 192.168.20.157:55553, ignoring
> 29/11/2013 16:07:16 :: invalid line ".org.apache.cassandra.metrics.ColumnFamily.mykeyspace.some_cf.EstimatedColumnCountHistogram.value
[J@290703a4 1385741236"received from client 192.168.20.157:55553, ignoring
> 29/11/2013 16:07:16 :: invalid line ".org.apache.cassandra.metrics.ColumnFamily.mykeyspace.some_cf.EstimatedRowSizeHistogram.value
[J@b801907 1385741236"received from client 192.168.20.157:55553, ignoring
> {code}
> Then a quick search through Cassandre code confirmed that there is a number of histograms
created as Gauge with long[] data. So, when they are serialized by  GraphiteReporter they
are just printed as long[].toString(), making these metrics useless.
> I am not sure what would be the best solution to it. I do see some histograms (LiveScannedHistogram
etc) that are implemented differently and they are properly sent to Graphite.



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