[jira] Updated: (HADOOP-1245) value for mapred.tasktracker.tasks.maximum taken from two different sources

["Rick Cox (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HADOOP-1245?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Rick Cox updated HADOOP-1245:
-----------------------------

    Attachment: tasktracker-max-tasks-1245.patch

Here's a patch implementing the approach described in the last comment. It also includes web UI updates to display the per tasktracker max-tasks setting.

> value for mapred.tasktracker.tasks.maximum taken from two different sources
> ---------------------------------------------------------------------------
>
>                 Key: HADOOP-1245
>                 URL: https://issues.apache.org/jira/browse/HADOOP-1245
>             Project: Hadoop
>          Issue Type: Bug
>          Components: mapred
>    Affects Versions: 0.12.3
>            Reporter: Michael Bieniosek
>         Attachments: tasktracker-max-tasks-1245.patch
>
>
> I want to create a cluster with machines with different numbers of CPUs.  Consequently, each machine should have a different value for mapred.tasktracker.tasks.maximum, since my map tasks are CPU bound.
> However, hadoop uses BOTH the values for mapred.tasktracker.tasks.maximum on the jobtracker and the tasktracker.  
> When a new job starts up, the jobtracker uses its (single) value for mapred.tasktracker.tasks.maximum to assign tasks.  This means that each tasktracker gets the same number of tasks, regardless of how I configured that particular machine.
> After the first task finishes on each tasktracker, the tasktracker will request new tasks from the jobtracker according to the tasktracker's value for mapred.tasktracker.tasks.maximum.  So after the first round of map tasks is done, the cluster reverts to a mode that works well for heterogeneous clusters.
> The jobtracker should not consult its config for the value of mapred.tasktracker.tasks.maximum.  It should assign tasks (or allow tasktrackers to request tasks) according to each tasktracker's value of mapred.tasktracker.tasks.maximum.

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