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From "Todd Lipcon (JIRA)" <j...@apache.org>
Subject [jira] Commented: (MAPREDUCE-2261) Fair Multiple Task Assignment Scheduler (Assigning multiple tasks per heart beat)
Date Fri, 25 Feb 2011 07:06:38 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-2261?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12999238#comment-12999238

Todd Lipcon commented on MAPREDUCE-2261:

MAPREDUCE-706 was a poorly named JIRA. It actually rewrote much of the fair scheduler, including
adding this feature. In trunk, look at the usage of the mapAssignCap and reduceAssignCap variables.
You'll see that assignTasks loops until the specified number of tasks have been assigned or
the load manager indicates that no more can be assigned.

> Fair Multiple Task Assignment Scheduler (Assigning multiple tasks per heart beat)
> ---------------------------------------------------------------------------------
>                 Key: MAPREDUCE-2261
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-2261
>             Project: Hadoop Map/Reduce
>          Issue Type: New Feature
>    Affects Versions: 0.21.0
>            Reporter: Devaraj K
>       Functionality wise the Fair Multiple Task Assignment Scheduler behaves the same
way except the assignment of Tasks. Instead of assigning a single Task per heartbeat, it checks
for all the jobs if any local or non-local Task that can be launched.
> Fair Multiple Task Assignment Scheduler has the advantage of assigning multiple jobs
per heart beat interval depending upon the slots available on the Task Tracker, by configuring
the number of parallel tasks to be executed in a Task Tracker at any point of time. The advantages
are as follows:
> a) Parallel Execution allows tasks be to submitted and processed in parallel independent
of the status of other tasks.
> b) More number of tasks is assigned in a heartbeat interval and consequently multitasking
capability increases.
> c) With multi task assignment, Task Tracker efficiency is increased.

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