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Date: Tue, 27 Apr 2010 05:51:34 -0400 (EDT)
From: "Vinod K V (JIRA)" <jira@apache.org>
To: mapreduce-issues@hadoop.apache.org
Subject: [jira] Commented: (MAPREDUCE-1397) NullPointerException observed
 during task failures
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    [ https://issues.apache.org/jira/browse/MAPREDUCE-1397?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12861335#action_12861335 ] 

Vinod K V commented on MAPREDUCE-1397:
--------------------------------------

Patch looks good. I myself reviewed the patch for ydist and the fact that the same patch applies cleanly on trunk too helps!

But like I pointed before the interactions of JvmManager with TaskRunner, TaskTracker and TaskController are really nasty and unmaintainable. Will open a JIRA for refactoring so as to align these interfaces better.

We can't wait for the refactor, I am going to commit this patch for now.

> NullPointerException observed during task failures
> --------------------------------------------------
>
>                 Key: MAPREDUCE-1397
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-1397
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>          Components: tasktracker
>    Affects Versions: 0.20.1
>            Reporter: Ramya R
>            Assignee: Amareshwari Sriramadasu
>            Priority: Minor
>             Fix For: 0.22.0
>
>         Attachments: patch-1397-1.txt, patch-1397-2.txt, patch-1397-3.txt, patch-1397-ydist.txt, patch-1397.txt
>
>
> In an environment where many jobs are killed simultaneously, NPEs are observed in the TT/JT logs when a task fails. The situation is aggravated when the taskcontroller.cfg is not configured properly. Below is the exception obtained:
> {noformat}
> INFO org.apache.hadoop.mapred.TaskInProgress: Error from <attempt_ID>:
> java.lang.Throwable: Child Error
>         at org.apache.hadoop.mapred.TaskRunner.run(TaskRunner.java:529)
> Caused by: java.lang.NullPointerException
>         at org.apache.hadoop.mapred.JvmManager$JvmManagerForType.getDetails(JvmManager.java:329)
>         at org.apache.hadoop.mapred.JvmManager$JvmManagerForType.reapJvm(JvmManager.java:315)
>         at org.apache.hadoop.mapred.JvmManager$JvmManagerForType.access$000(JvmManager.java:146)
>         at org.apache.hadoop.mapred.JvmManager.launchJvm(JvmManager.java:109)
>         at org.apache.hadoop.mapred.TaskRunner.run(TaskRunner.java:502)
>  {noformat}

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