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From "Jing Zhao (JIRA)" <j...@apache.org>
Subject [jira] [Comment Edited] (HDFS-8272) Erasure Coding: simplify the retry logic in DFSStripedInputStream (stateful read)
Date Wed, 29 Apr 2015 20:04:07 GMT

    [ https://issues.apache.org/jira/browse/HDFS-8272?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14520095#comment-14520095
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Jing Zhao edited comment on HDFS-8272 at 4/29/15 8:03 PM:
----------------------------------------------------------

Thanks for the review, Zhe and Yi! I just merged HDFS-8280 into HDFS-7285 branch. Upload the
patch excluding the changes in DFSInputStream. Also fix the bug pointed out by Yi.

About the {{seekToBlockSource}}, I think it may be better to remove it:
# With decoding functionality we do not need to spend more time trying our luck on the same
DN.
# Currently calling {{seekToBlockSource}} will cause all the current block readers to be closed
(since {{blockSeekTo}} will call {{closeCurrentBlockReaders}}). To fix this we need to add
extra complexity so as to make sure only one block reader is retried.
How about removing it by now and we can add it back if necessary in the future?


was (Author: jingzhao):
Thanks for the review, Zhe and Yi! I just merged HDFS-8280 into HDFS-7285 branch. Upload the
patch excluding the changes in DFSInputStream. Also fix the bug pointed out by Yi.

About the {{seekToBlockSource}}, I think it may be better to remove it by now:
# With decoding functionality we do not need to spend more time trying our luck on the same
DN.
# Currently calling {{seekToBlockSource}} will cause all the current block readers to be closed
(since {{blockSeekTo}} will call {{closeCurrentBlockReaders}}). To fix this we need to add
extra complexity so as to make sure only one block reader is retried.

> Erasure Coding: simplify the retry logic in DFSStripedInputStream (stateful read)
> ---------------------------------------------------------------------------------
>
>                 Key: HDFS-8272
>                 URL: https://issues.apache.org/jira/browse/HDFS-8272
>             Project: Hadoop HDFS
>          Issue Type: Sub-task
>            Reporter: Jing Zhao
>            Assignee: Jing Zhao
>         Attachments: HDFS-8272.002.patch, h8272-HDFS-7285.000.patch, h8272-HDFS-7285.001.patch
>
>
> Currently in DFSStripedInputStream the retry logic is still the same with DFSInputStream.
More specifically, every failed read will try to search for another source node. And an exception
is thrown when no new source node can be identified. This logic is not appropriate for EC
inputstream and can be simplified.



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