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https://issues.apache.org/jira/browse/FLINK-4245?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15424431#comment-15424431
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ASF GitHub Bot commented on FLINK-4245:
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Github user StephanEwen commented on the issue:
https://github.com/apache/flink/pull/2300
Looks mostly good. I noticed a few things:
I am not quite sure about the lazy initialization. The idea is good, but
the current double-check-locking pattern is not multi-thread safe
(http://www.cs.umd.edu/~pugh/java/memoryModel/DoubleCheckedLocking.html).
Either we make each access a little more expensive (declare the field
`volatile`), or we eagerly initialize the maps.
As a followup, we should probably look into adjusting the JMX reporter. Is
there a way we can expose all tags?
Can you also rebase this to the latest master? It has a bunch of merge
conflicts right now, when trying to test it.
> Metric naming improvements
> --------------------------
>
> Key: FLINK-4245
> URL: https://issues.apache.org/jira/browse/FLINK-4245
> Project: Flink
> Issue Type: Improvement
> Components: Metrics
> Reporter: Stephan Ewen
>
> A metric currently has two parts to it:
> - The name of that particular metric
> - The "scope" (or namespace), defined by the group that contains the metric.
> A metric group actually always implicitly has a map of naming "tags", like:
> - taskmanager_host : <some-hostname>
> - taskmanager_id : <id>
> - task_name : "map() -> filter()"
> We derive the scope from that map, following the defined scope formats.
> For JMX (and some users that use JMX), it would be natural to expose that map
> of tags. Some users reconstruct that map by parsing the metric scope. JMX, we
> can expose a metric like:
> - domain: "taskmanager.task.operator.io"
> - name: "numRecordsIn"
> - tags: { "hostname" -> "localhost", "operator_name" -> "map() at
> X.java:123", ... }
> For many other reporters, the formatted scope makes a lot of sense, since
> they think only in terms of (scope, metric-name).
> We may even have the formatted scope in JMX as well (in the domain), if we
> want to go that route.
> [~jgrier] and [~Zentol] - what do you think about that?
> [~mdaxini] Does that match your use of the metrics?
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