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https://issues.apache.org/jira/browse/HDFS-13702?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16525612#comment-16525612
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stack commented on HDFS-13702:
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bq. I do want a trace layer in there; I do want it broader than just HDFS, and
I do want it to be used from the layers above.
Me too.
bq. Otherwise: it'll get cut, nobody will replace it, and it'll get lost in
folklore.
Better this than a dead, disabled lib burning everyone's CPU to no end. Even
when enabled, as is, it is of little to no value. Trace in hdfs is in need of
work but it has been suffering neglect since Colin's add.
bq. This is something to talk about at a broader level than a JIRA;
I can start a thread. Suggest this discussion not block this patch? Or, add in
placeholders/comments for the trace points removed here?
Thanks [~ste...@apache.org]
> HTrace hooks taking 10-15% CPU in DFS client when disabled
> ----------------------------------------------------------
>
> Key: HDFS-13702
> URL: https://issues.apache.org/jira/browse/HDFS-13702
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: performance
> Affects Versions: 3.0.0
> Reporter: Todd Lipcon
> Assignee: Todd Lipcon
> Priority: Major
> Attachments: hdfs-13702.patch, hdfs-13702.patch, hdfs-13702.patch
>
>
> I am seeing DFSClient.newReaderTraceScope take ~15% CPU in a teravalidate
> workload even when HTrace is disabled. This is because it stringifies several
> integers. We should avoid all allocation and stringification when htrace is
> disabled.
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