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Date: Thu, 25 Feb 2010 18:36:28 +0000 (UTC)
From: "Hong Tang (JIRA)" <jira@apache.org>
To: mapreduce-issues@hadoop.apache.org
Subject: [jira] Commented: (MAPREDUCE-1221) Kill tasks on a node if the free
 physical memory on that machine falls below a configured threshold
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    [ https://issues.apache.org/jira/browse/MAPREDUCE-1221?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12838470#action_12838470 ] 

Hong Tang commented on MAPREDUCE-1221:
--------------------------------------

@arun, I think we need both - with per-task resource containment at the high level, and os-level protection at the low level. In this jira, let's focus on the low-level protection) and we can have a separate jira to track the per-task resource containment. 

> Kill tasks on a node if the free physical memory on that machine falls below a configured threshold
> ---------------------------------------------------------------------------------------------------
>
>                 Key: MAPREDUCE-1221
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-1221
>             Project: Hadoop Map/Reduce
>          Issue Type: Improvement
>          Components: tasktracker
>    Affects Versions: 0.22.0
>            Reporter: dhruba borthakur
>            Assignee: Scott Chen
>             Fix For: 0.22.0
>
>         Attachments: MAPREDUCE-1221-v1.patch, MAPREDUCE-1221-v2.patch, MAPREDUCE-1221-v3.patch
>
>
> The TaskTracker currently supports killing tasks if the virtual memory of a task exceeds a set of configured thresholds. I would like to extend this feature to enable killing tasks if the physical memory used by that task exceeds a certain threshold.
> On a certain operating system (guess?), if user space processes start using lots of memory, the machine hangs and dies quickly. This means that we would like to prevent map-reduce jobs from triggering this condition. From my understanding, the killing-based-on-virtual-memory-limits (HADOOP-5883) were designed to address this problem. This works well when most map-reduce jobs are Java jobs and have well-defined -Xmx parameters that specify the max virtual memory for each task. On the other hand, if each task forks off mappers/reducers written in other languages (python/php, etc), the total virtual memory usage of the process-subtree varies greatly. In these cases, it is better to use kill-tasks-using-physical-memory-limits.

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