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From "Kihwal Lee (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-3541) Deadlock between recovery, xceiver and packet responder
Date Tue, 26 Jun 2012 03:16:47 GMT

    [ https://issues.apache.org/jira/browse/HDFS-3541?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13401135#comment-13401135
] 

Kihwal Lee commented on HDFS-3541:
----------------------------------

The patch looks okay but I was wondering whether the test can be improved. 

The test in the current patch does not directly recreate the original race condition. Probably
an artificial deadlock can be created by creating a thread which does sleep and then kills
the writer inside a {{synchronized(datanode.data)}} block. While it's sleeping, another thread
could try closing the {{DFSOutputStream}}. This should fail when the writer (i.e. the {{DataXceiver}}
thread) is killed and streams get closed.  After this we could verify the block is not finalized.
Then we know the {{PacketResponder}} thread didn't finalize the block. 

Does it make sense?

                
> Deadlock between recovery, xceiver and packet responder
> -------------------------------------------------------
>
>                 Key: HDFS-3541
>                 URL: https://issues.apache.org/jira/browse/HDFS-3541
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: data-node
>    Affects Versions: 0.23.3, 2.0.1-alpha
>            Reporter: suja s
>            Assignee: Vinay
>         Attachments: DN_dump.rar, HDFS-3541.patch
>
>
> Block Recovery initiated while write in progress at Datanode side. Found a lock between
recovery, xceiver and packet responder.

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