[jira] Commented: (HADOOP-3687) Ability to pause/resume tasks

["Matei Zaharia (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HADOOP-3687?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12646425#action_12646425 ] 

Matei Zaharia commented on HADOOP-3687:
---------------------------------------

The really hard challenge with pausing, in my opinion, will be how to decide when to resume the tasks or when to kill them. It's not clear that if you pause a task on some machine, you'll get the opportunity to run it again. In fact, maybe another machine becomes free and you'd be better off running the task on that one. So the whole scheduling problem becomes more difficult.

Another fix that we really have to strive for is making reduces smaller, e.g. by separating the copy phase into its own set of tasks (Joydeep has posted some comments on this in the MapReduce 2.0 discussion).

> Ability to pause/resume tasks
> -----------------------------
>
>                 Key: HADOOP-3687
>                 URL: https://issues.apache.org/jira/browse/HADOOP-3687
>             Project: Hadoop Core
>          Issue Type: New Feature
>          Components: mapred
>            Reporter: Chris Smith
>            Assignee: Chris Smith
>            Priority: Minor
>         Attachments: hadoop-pausing.8.trunk.patch
>
>
> It would be nice to be able to pause (and subsequently resume) tasks that are currently running, in order to allow tasks from higher priority jobs to execute. At present it is quite easy for long-running tasks from low priority jobs to block a task from a newer high priority job, and there is no way to force the execution of the high priority task without killing the low priority jobs.

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