[ 
https://issues.apache.org/jira/browse/MAPREDUCE-1398?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12834157#action_12834157
 ] 

Hemanth Yamijala commented on MAPREDUCE-1398:
---------------------------------------------

bq. The patch did not introduce any new unsynchronized code.

I verified this. Also, per comment from Chris in MAPREDUCE-1497, IndexCache is 
probably already thead-safe. Hence, this might be a legitimate case of 
suppressing findbugs warning. Based on this, I think the patch is ready for 
commit.

> 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.

-- 
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.

Reply via email to