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https://issues.apache.org/jira/browse/HDFS-10742?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15449980#comment-15449980
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Arpit Agarwal commented on HDFS-10742:
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Hi [~vagarychen], a couple of comments:
# {{check()}} should have minimal overhead if the lock was not held for more
lockWarningThresholdMs which will be the common case. We can simplify the patch
quite a bit and just add logging along with the caller stack trace if the lock
was held for too long. We can extend it later if we want to add performance
statistics but we'd have to do it in a way that avoids object allocations.
# InstrumentedLock should probably not extend the concrete class
AutoCloseableLock. We can make InstrumentedLock a separate class. or
alternatively AutoCloseableLock a Java interface with multiple implementations.
bq. but in the context of a patch generating thread stacks and maintaining
persistent maps of timestamps, it's absurd to debate any of this.
Yes I agree. We should avoid that overhead.
> Measurement of lock held time in FsDatasetImpl
> ----------------------------------------------
>
> Key: HDFS-10742
> URL: https://issues.apache.org/jira/browse/HDFS-10742
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: datanode
> Affects Versions: 3.0.0-alpha2
> Reporter: Chen Liang
> Assignee: Chen Liang
> Attachments: HDFS-10742.001.patch, HDFS-10742.002.patch,
> HDFS-10742.003.patch, HDFS-10742.004.patch, HDFS-10742.005.patch,
> HDFS-10742.006.patch, HDFS-10742.007.patch, HDFS-10742.008.patch
>
>
> This JIRA proposes to measure the time the of lock of {{FsDatasetImpl}} is
> held by a thread. Doing so will allow us to measure lock statistics.
> This can be done by extending the {{AutoCloseableLock}} lock object in
> {{FsDatasetImpl}}. In the future we can also consider replacing the lock with
> a read-write lock.
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