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https://issues.apache.org/jira/browse/HDFS-8088?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14494783#comment-14494783
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Josh Elser commented on HDFS-8088:
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bq. Keep in mind that doing a write in HDFS just hands the data off to a
background thread called DataStreamer. which writes it out asynchronously
Ahh, good point. I didn't fully connect the dots in my head when I was
initially guessing.
bq. I'm inclined to lean more towards goal #1 (figure out why specific requests
had high latency) than goal #2
Agreed.
bq. I do think maybe we should target 2.7.1 for some of these changes since I
need to think through everything
I would be very happy to see this (as well as HDFS-8026) land into 2.7.1.
bq. I'd also like to run some patches by you guys to see if it improves the
usefulness of HTrace to you.
Happy to do so. I'm sure [~billie.rinaldi], as well as some other Accumulo
folks, would be interested.
bq. also I am at a conference now, so I apologize if my replies are slow!
No worries! Assuming you're at ApacheCon (and presumably speaking?), I hope it
goes well. Enjoy, and we can catch up when you're on a normal schedule again.
> 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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