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From "Zhe Zhang (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-6450) Support non-positional hedged reads in HDFS
Date Sat, 07 Mar 2015 02:56:40 GMT

    [ https://issues.apache.org/jira/browse/HDFS-6450?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14351346#comment-14351346
] 

Zhe Zhang commented on HDFS-6450:
---------------------------------

Thanks for the suggestion Colin. Hedged pread is already handling BlockReaderLocal (by wrapping
it as a Future). I guess it's reasonable to do the same for non-positional read too? 

Is it correct to understand hedged vs. non-hedged and positional vs. non-positional as orthogonal
dimensions? If so, the only new requirement in hedged non-positional read is to utilize and
maintain the states (pos, blockReader).

I'm still getting myself around this complex reader code. So please let me know if I missed
something.

> Support non-positional hedged reads in HDFS
> -------------------------------------------
>
>                 Key: HDFS-6450
>                 URL: https://issues.apache.org/jira/browse/HDFS-6450
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>    Affects Versions: 2.4.0
>            Reporter: Colin Patrick McCabe
>            Assignee: Liang Xie
>         Attachments: HDFS-6450-like-pread.txt
>
>
> HDFS-5776 added support for hedged positional reads.  We should also support hedged non-position
reads (aka regular reads).



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