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From "Tsz Wo Nicholas Sze (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-8287) DFSStripedOutputStream.writeChunk should not wait for writing parity
Date Thu, 10 Sep 2015 10:48:46 GMT

    [ https://issues.apache.org/jira/browse/HDFS-8287?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14738573#comment-14738573
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Tsz Wo Nicholas Sze commented on HDFS-8287:
-------------------------------------------

Yes, it is reasonable.  The deadlock here seems that writeParity(i, buffers[i], cb.getChecksumArray(i)),
which is supposed to hold the DFSStripedOutputStream lock, cannot be called asynchronously.
 We should only generate the parity asynchronously but write parity synchronously.

> 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,
HDFS-8287-HDFS-7285.06.patch, HDFS-8287-HDFS-7285.07.patch, HDFS-8287-HDFS-7285.08.patch,
HDFS-8287-HDFS-7285.WIP.patch, jstack-dump.txt
>
>
> 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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