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https://issues.apache.org/jira/browse/HADOOP-4035?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12642899#action_12642899
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Vinod K V commented on HADOOP-4035:
-----------------------------------

bq. [....] the job should not be accepted by the JT in submitJob(). If the 
limit is not set, jobs cannot be rejected based on their memory requirements.
Irrespective of the method to specify the maximum limits on job requirements to 
prevent gaming of the system, either via a configuration or by calculating it 
dynamically, the job rejection should not be done by JT, but by our scheduler 
itself. Clearly, this maximum limit is owned by our scheduler.

> 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: 0.20.0
>
>         Attachments: 4035.1.patch, HADOOP-4035-20080918.1.txt, 
> HADOOP-4035-20081006.1.txt, HADOOP-4035-20081006.txt, HADOOP-4035-20081008.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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