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https://issues.apache.org/jira/browse/HDFS-8287?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14738207#comment-14738207
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Kai Sasaki commented on HDFS-8287:
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{{writeChunk}} obtains a lock of {{DFSStripedOutputStreamer}} because this
method is {{synchronized}}.
And inside of {{Callable<Void>}}, {{setCurrentStreamer}} also tries to obtain
the lock of {{DFSStripedOutputStream}}. This may cause dead lock. Although main
thread can keep running after submitting {{Callable<Void>}}, it must wait at
next {{DoubleCellBuffers#rollBuffers}} because it calls {{waitForReady}} and
{{Callable<Void>}} can not progress, so the main thread also cannot progress
here.
According to the thread dump, I can decide it. Does this assumption seems to be
reasonable?
> 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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