[jira] [Commented] (HDFS-6450) Support non-positional hedged reads in HDFS

["Liang Xie (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HDFS-6450?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14053324#comment-14053324 ] 

Liang Xie commented on HDFS-6450:
---------------------------------

[~cmccabe] [~saint.ack@gmail.com] I made a prototype already(still adding more test cases), but i think we need to clear one thing right now: how to handle the block reader for read().
In current impl, the read() maintains a blockreader to reuse for furture read calls, and pread() will create a new blockreader in each call always.
So if we want to enhance read() to have hedged read ability, should we assign the first completed read request's block reader to above maintained blockreader variable?(i guess most of situations, this behavior probably will be like change the local block reader to a remote  block reader?)

> 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
>
> HDFS-5776 added support for hedged positional reads.  We should also support hedged non-position reads (aka regular reads).



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