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https://issues.apache.org/jira/browse/HADOOP-7507?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13099589#comment-13099589
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Todd Lipcon commented on HADOOP-7507:
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I was thinking the default for the jvm prefix would be uncommented in the file.
So, if you enable Ganglia metrics, it's set up correctly by default with no
other changes. You could uncomment all of the lines, to be consistent, right?
the uncommented line with an empty value would be equivalent to the
commented-out line?
For the method being accessible to tests, I think the @VisibleForTests
annotation from Guava is more appropriate.
> jvm metrics all use the same namespace
> --------------------------------------
>
> Key: HADOOP-7507
> URL: https://issues.apache.org/jira/browse/HADOOP-7507
> Project: Hadoop Common
> Issue Type: Bug
> Components: metrics
> Affects Versions: 0.20.2
> Reporter: Jeff Bean
> Assignee: Alejandro Abdelnur
> Fix For: 0.23.0, 0.24.0
>
> Attachments: HADOOP-7507-v2.patch, HADOOP-7507v1.patch,
> HADOOP-7507v3.patch, HADOOP-7507v4.patch, HADOOP-7507v5.patch,
> HADOOP-7507v6.patch, HADOOP-7507v7.patch, JvmMetrics.java,
> hadoop-metrics.properties, screenshot-1.jpg
>
>
> Ganglia jvm metrics don't make sense because it's not clear which java
> process the metrics refer to. In fact, all hadoop java processes running on a
> node report their jvm metrics to the same namespace.
> The metrics are exposed by the "jvm" context in JvmMetrics.java. This leads
> to confusing and nonsensical graphs in ganglia and maybe other monitoring
> tools.
> One way to fix this is to make sure the process name is reported in the jvm
> context, making it clear which process is associated with the context, and
> separating out the jvm metrics per process.
> This is marked as an "incompatible change" because the fix provided removes
> the JVM metrics and replaces it with process-specific metrics.
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