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https://issues.apache.org/jira/browse/CASSANDRA-6423?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13835475#comment-13835475
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Nikolai Grigoriev commented on CASSANDRA-6423:
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I think the consumers cannot really be expected to understand
"[J@290703a4"...Knowing how the serialization of the metrics works, can you
really expect that your metric defined as long[] would be serialized as
something meaningful?
> 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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