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https://issues.apache.org/jira/browse/HDFS-8088?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14487376#comment-14487376
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Yi Liu commented on HDFS-8088:
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The patch needs to be rebased.
I agree that we don't need to have trace span for each read, which will affect
performance. I have checked that we have not added trace span for {{pread}}.
The patch looks good to me.
BTW,
{code}
- int hedgedReadId = 0;
+ int hedgedReadId = 1;
{code}
This change is not necessary.
> Reduce the number of HTrace spans generated by HDFS reads
> ---------------------------------------------------------
>
> Key: HDFS-8088
> URL: https://issues.apache.org/jira/browse/HDFS-8088
> Project: Hadoop HDFS
> Issue Type: Improvement
> Reporter: Colin Patrick McCabe
> Assignee: Colin Patrick McCabe
> Attachments: HDFS-8088.001.patch
>
>
> HDFS generates too many trace spans on read right now. Every call to read()
> we make generates its own span, which is not very practical for things like
> HBase or Accumulo that do many such reads as part of a single operation.
> Instead of tracing every call to read(), we should only trace the cases where
> we refill the buffer inside a BlockReader.
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