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https://issues.apache.org/jira/browse/HDFS-9576?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15098719#comment-15098719
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Zhe Zhang commented on HDFS-9576:
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Thanks for the review Colin.
bq. Can we use "pos" instead?
Good point. Will update in next rev.
Tracing the "requested length" is mostly for profiling application behavior. I
agree that the "returned length" is what ultimately matters in the particular
scenario being traced. But "requested length" gives insights on what-if
analysis -- e.g. a different system could return more data and fully satisfy
the request.
So how about only reporting "returned length" if it's different from requested?
> HTrace: collect position/length information on read operations
> --------------------------------------------------------------
>
> Key: HDFS-9576
> URL: https://issues.apache.org/jira/browse/HDFS-9576
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: hdfs-client, tracing
> Affects Versions: 2.7.1
> Reporter: Zhe Zhang
> Assignee: Zhe Zhang
> Attachments: HDFS-9576.00.patch, HDFS-9576.01.patch,
> HDFS-9576.02.patch, HDFS-9576.03.patch, HDFS-9576.04.patch, HDFS-9576.05.patch
>
>
> HTrace currently collects the path of each read operation (both stateful and
> position reads). To better understand applications' I/O behavior, it is also
> useful to track the position and length of read operations.
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