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Date: Mon, 20 Dec 2010 16:49:02 -0500 (EST)
From: "Amit Nithian (JIRA)" <jira@apache.org>
To: hdfs-issues@hadoop.apache.org
Subject: [jira] Updated: (HDFS-1542) Deadlock in Configuration.writeXml when
 serialized form is larger than one DFS block
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     [ https://issues.apache.org/jira/browse/HDFS-1542?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Amit Nithian updated HDFS-1542:
-------------------------------

    Attachment: deadlock.txt

Attached is an example of the thread dump of the jobtracker when submitting a job that causes the tracker to deadlock. This is consistent with the one that was posted on the mailing lists to kick off this issue. I tried to increase my block size to 128M to no avail. 

BTW how can I use your test program to reproduce the problem on my cluster? I successfully ran it locally but am not sure how I can run this in a distributed mode to test.

> Deadlock in Configuration.writeXml when serialized form is larger than one DFS block
> ------------------------------------------------------------------------------------
>
>                 Key: HDFS-1542
>                 URL: https://issues.apache.org/jira/browse/HDFS-1542
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: hdfs client
>    Affects Versions: 0.20.2, 0.22.0, 0.23.0
>            Reporter: Todd Lipcon
>            Priority: Critical
>         Attachments: deadlock.txt, Test.java
>
>
> Configuration.writeXml holds a lock on itself and then writes the XML to an output stream, during which DFSOutputStream will try to get a lock on ackQueue/dataQueue. Meanwihle the DataStreamer thread will call functions like conf.getInt() and deadlock against the other thread, since it could be the same conf object.
> This causes a deterministic deadlock whenever the serialized form is larger than block size.

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