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https://issues.apache.org/jira/browse/HDFS-6591?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14046875#comment-14046875
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Liang Xie commented on HDFS-6591:
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[[email protected]], good idea!
[~cnauroth], will dive into it definitely, nice finding! so that memory copy
optimization is immature ? :) i will rethink it later. (I assumed even two
threads mutate the buffer in a face condition, the final result should be same
due to that two threads have read out a same source result.)
> while loop is executed tens of thousands of times in Hedged Read
> ------------------------------------------------------------------
>
> Key: HDFS-6591
> URL: https://issues.apache.org/jira/browse/HDFS-6591
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: hdfs-client
> Affects Versions: 2.4.0
> Reporter: LiuLei
> Assignee: Liang Xie
> Attachments: HDFS-6591-v2.txt, HDFS-6591-v3.txt, HDFS-6591.txt,
> LoopTooManyTimesTestCase.patch
>
>
> I download hadoop-2.4.1-rc1 code from
> http://people.apache.org/~acmurthy/hadoop-2.4.1-rc1/, I test the Hedged
> Read. I find the while loop in hedgedFetchBlockByteRange method is executed
> tens of thousands of times.
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