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https://issues.apache.org/jira/browse/HADOOP-4035?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12635445#action_12635445
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Owen O'Malley commented on HADOOP-4035:
---------------------------------------

I think it is important that we not starve jobs, so I think we should not take 
the next job's task, if the current job's task doesn't fit. I've also filed 
HADOOP-4306 to change the disk space monitoring the same way.

It probably makes sense in the future, to have a special case if the 
TaskTracker is job's task will never fit on this TaskTracker and let other low 
priority jobs use it. But, it should be a different jira.

> Modify the capacity scheduler (HADOOP-3445) to schedule tasks based on memory 
> requirements and task trackers free memory
> ------------------------------------------------------------------------------------------------------------------------
>
>                 Key: HADOOP-4035
>                 URL: https://issues.apache.org/jira/browse/HADOOP-4035
>             Project: Hadoop Core
>          Issue Type: Bug
>          Components: contrib/capacity-sched
>    Affects Versions: 0.19.0
>            Reporter: Hemanth Yamijala
>            Assignee: Vinod K V
>            Priority: Blocker
>             Fix For: 0.19.0
>
>         Attachments: 4035.1.patch, HADOOP-4035-20080918.1.txt
>
>
> HADOOP-3759 introduced configuration variables that can be used to specify 
> memory requirements for jobs, and also modified the tasktrackers to report 
> their free memory. The capacity scheduler in HADOOP-3445 should schedule 
> tasks based on these parameters. A task that is scheduled on a TT that uses 
> more than the default amount of memory per slot can be viewed as effectively 
> using more than one slot, as it would decrease the amount of free memory on 
> the TT by more than the default amount while it runs. The scheduler should 
> make the used capacity account for this additional usage while enforcing 
> limits, etc.

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