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Date: Wed, 14 Jun 2006 06:32:31 +0000 (GMT+00:00)
From: "Owen O'Malley (JIRA)" <jira@apache.org>
To: hadoop-dev@lucene.apache.org
Subject: [jira] Updated: (HADOOP-135) Potential deadlock in JobTracker.
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     [ http://issues.apache.org/jira/browse/HADOOP-135?page=all ]

Owen O'Malley updated HADOOP-135:
---------------------------------

    Attachment: fix-lock-order.patch

Reverse the order of locking for the two fields so that they are always acquired in the same order.

> Potential deadlock in JobTracker.
> ---------------------------------
>
>          Key: HADOOP-135
>          URL: http://issues.apache.org/jira/browse/HADOOP-135
>      Project: Hadoop
>         Type: Bug

>   Components: mapred
>     Versions: 0.1.0
>     Reporter: Konstantin Shvachko
>     Assignee: Owen O'Malley
>      Fix For: 0.4.0
>  Attachments: fix-lock-order.patch
>
> org.apache.hadoop.mapred.JobTracker.RetireJobs.run()
> locks resources in this order
>                 synchronized (jobs) {
>                     synchronized (jobInitQueue) {
>                         synchronized (jobsByArrival) {
> org.apache.hadoop.mapred.JobTracker.submitJob()
> locks resources in a different order
>         synchronized (jobs) {
>             synchronized (jobsByArrival) {
>                 synchronized (jobInitQueue) {
> This potentially can lead to a deadlock.
> Unless there is common lock on top of it in which case these
> three locks are redundant.

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