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https://issues.apache.org/jira/browse/HDFS-11615?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Erik Krogen updated HDFS-11615:
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Attachment: HDFS-11615.000.patch
Attaching v000 patch which exports these values in microseconds, which is more
relevant at the timescale at which these operations occur. Some quick tests
indicate the cheapest operations fall in the tens-of-microseconds range so
nanosecond precision seems unnecessary. Added a new unit test and tested on a
minicluster.
> FSNamesystemLock metrics can be inaccurate due to millisecond precision
> -----------------------------------------------------------------------
>
> Key: HDFS-11615
> URL: https://issues.apache.org/jira/browse/HDFS-11615
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: hdfs
> Affects Versions: 2.7.4
> Reporter: Erik Krogen
> Assignee: Erik Krogen
> Attachments: HDFS-11615.000.patch
>
>
> Currently the {{FSNamesystemLock}} metrics created in HDFS-10872 track the
> lock hold time using {{Timer.monotonicNow()}}, which has millisecond-level
> precision. However, many of these operations hold the lock for less than a
> millisecond, making these metrics inaccurate. We should instead use
> {{System.nanoTime()}} for higher accuracy.
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