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Date: Mon, 14 Jul 2008 23:45:31 -0700 (PDT)
From: "Vivek Ratan (JIRA)" <jira@apache.org>
To: core-dev@hadoop.apache.org
Subject: [jira] Commented: (HADOOP-3740) Make JobInProgress pluggable
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    [ https://issues.apache.org/jira/browse/HADOOP-3740?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12613537#action_12613537 ] 

Vivek Ratan commented on HADOOP-3740:
-------------------------------------

bq. I dont think allowing user code to run in JT is a good idea.

I wasn't referring to code written by a user (a person who uses Hadoop). I was talking of code written by a Hadoop developer. The Scheduling flow will provide hooks for developers to plug in their own code. 

> Make JobInProgress pluggable
> ----------------------------
>
>                 Key: HADOOP-3740
>                 URL: https://issues.apache.org/jira/browse/HADOOP-3740
>             Project: Hadoop Core
>          Issue Type: Improvement
>          Components: mapred
>         Environment: all
>            Reporter: Alejandro Abdelnur
>
> By allowing a pluggable JobInProgess it will be possible for provide implementations that can do a sophisticated task provisioning to the JobTracker. 
> For example, by providing alternate implementations of the {{obtainNewMapTask}}, {{obtainNewReduceTask}} and {{updateTaskInProgress}} it would be possible to implement a license server that allows to throttle use of external resources (ie webservices, databases) so at any given time there are not more than N tasks using a given resource. For this a task could be tagged with the names of external resources and the license server would keep track of the tasks running per tag, if the counter reaches zero then the {{obtainNew*Task}} method could return NULL instead of a task.
>  

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