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https://issues.apache.org/jira/browse/MAPREDUCE-1398?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Amareshwari Sriramadasu updated MAPREDUCE-1398:
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    Attachment: patch-1398-ydist.txt

Patch for Yahoo! distribution. 
Ran ant test and test-patch.  test-patch failed because of MAPREDUCE-1497. All 
unit tests passed except TestNodeRefresh (due to MAPREDUCE-677). 
TestNodeRefresh passed when I reran the test.

> TaskLauncher remains stuck on tasks waiting for free nodes even if task is 
> killed.
> ----------------------------------------------------------------------------------
>
>                 Key: MAPREDUCE-1398
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-1398
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>          Components: tasktracker
>            Reporter: Hemanth Yamijala
>            Assignee: Amareshwari Sriramadasu
>             Fix For: 0.22.0
>
>         Attachments: patch-1398-1.txt, patch-1398-2.txt, 
> patch-1398-ydist.txt, patch-1398.txt
>
>
> Tasks could be assigned to trackers for slots that are running other tasks in 
> a commit pending state. This is an optimization done to pipeline task 
> assignment and launch. When the task reaches the tracker, it waits until 
> sufficient slots become free for it. This wait is done in the TaskLauncher 
> thread. Now, while waiting, if the task is killed externally (maybe because 
> the job finishes, etc), the TaskLauncher is not notified of this. So, it 
> continues to wait for the killed task to get sufficient slots. If slots do 
> not become free for a long time, this would result in considerable delay in 
> waking up the TaskLauncher thread. If the waiting task happens to be a high 
> RAM task, then it is also wasteful, because by waking up, it can make way for 
> normal tasks that can run on the available number of slots.

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