[jira] Commented: (HADOOP-4931) Document TaskTracker's memory management functionality and CapacityScheduler's memory based scheduling.

["Hemanth Yamijala (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HADOOP-4931?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12665690#action_12665690 ] 

Hemanth Yamijala commented on HADOOP-4931:
------------------------------------------

Vivek, few comments:

- I think monitoring should be with cluster setup rather than with the map/reduce tutorial. This is because it is more of an admin feature. The user parameters for memory should be as you have defined in the map/reduce tutorial, and possibly we can link the monitoring section in the cluster setup guide for more details.
- "Users can, optionally, indicate the VM task-limit per job." I think we can use 'specify' instead of indicate, as it seems to describe things better.
- "To enable monitoring for a (TT)" should be "To enable monitoring for a TT"
- Some of the documented variable names and types need to be checked. For e.g. it is not mapred.tasktracker.virtualmemory.reserved, but mapred.tasktracker.vmem.reserved. The type is long and not int. I think the value is in bytes and not KB.
- We should mention that both monitoring and scheduling is only supported on the Linux platform right now.
- Can we add a note that in monitoring, when a task is killed, a message is logged so users can see it in the daemon logs.
- Some of the parameters are cluster wide parameters. For e.g. default vmem. It would be best to call this out explicitly.
- In the capacity scheduler documentation, I think limit and the percentage pmem in vmem are two separate configuration items where you are treating them as one.

> Document TaskTracker's memory management functionality and CapacityScheduler's memory based scheduling.
> -------------------------------------------------------------------------------------------------------
>
>                 Key: HADOOP-4931
>                 URL: https://issues.apache.org/jira/browse/HADOOP-4931
>             Project: Hadoop Core
>          Issue Type: Bug
>          Components: contrib/capacity-sched, mapred
>            Reporter: Vinod K V
>            Assignee: Vivek Ratan
>         Attachments: 4931.1.patch
>
>


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