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From "Jing Zhao (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-8287) DFSStripedOutputStream.writeChunk should not wait for writing parity
Date Wed, 02 Sep 2015 00:49:45 GMT

    [ https://issues.apache.org/jira/browse/HDFS-8287?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14726497#comment-14726497
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Jing Zhao commented on HDFS-8287:
---------------------------------

Thanks for working on this, Kai! I agree with Zhe's comments. Besides of that, some further
thoughts:
# Maybe it's better to wrap the two CellBuffers and logic of switching between them into a
single class named DoubleCellBuffer. An example in our current code base is {{EditsDoubleBuffer}}.
# Instead of having a specific daemon thread ParityGenerator, maybe we can use a {{CompletionService}}
to simplify the code. Also in this way it's easier to write code to wait for the writing of
the parity blocks to finish.

> DFSStripedOutputStream.writeChunk should not wait for writing parity 
> ---------------------------------------------------------------------
>
>                 Key: HDFS-8287
>                 URL: https://issues.apache.org/jira/browse/HDFS-8287
>             Project: Hadoop HDFS
>          Issue Type: Sub-task
>          Components: hdfs-client
>            Reporter: Tsz Wo Nicholas Sze
>            Assignee: Kai Sasaki
>         Attachments: HDFS-8287-HDFS-7285.00.patch, HDFS-8287-HDFS-7285.01.patch, HDFS-8287-HDFS-7285.02.patch,
HDFS-8287-HDFS-7285.03.patch, HDFS-8287-HDFS-7285.04.patch, HDFS-8287-HDFS-7285.05.patch
>
>
> When a stripping cell is full, writeChunk computes and generates parity packets.  It
sequentially calls waitAndQueuePacket so that user client cannot continue to write data until
it finishes.
> We should allow user client to continue writing instead but not blocking it when writing
parity.



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