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Date: Sat, 27 Feb 2010 01:12:05 +0000 (UTC)
From: "Todd Lipcon (JIRA)" <jira@apache.org>
To: mapreduce-issues@hadoop.apache.org
Subject: [jira] Commented: (MAPREDUCE-1304) Add counters for task time spent
 in GC
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    [ https://issues.apache.org/jira/browse/MAPREDUCE-1304?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12839108#action_12839108 ] 

Todd Lipcon commented on MAPREDUCE-1304:
----------------------------------------

Two questions:

- I don't know the Task code quite well enough, but will this still be set in the case that the task fails?
- Is it worth putting this in a separate thread in the Child interface so it actually gets incremented as the task goes, with each umbilical heartbeat? It would be nice to see this on a per-task basis when a task appears to be "stuck".

> Add counters for task time spent in GC
> --------------------------------------
>
>                 Key: MAPREDUCE-1304
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-1304
>             Project: Hadoop Map/Reduce
>          Issue Type: New Feature
>          Components: task
>            Reporter: Todd Lipcon
>            Assignee: Aaron Kimball
>         Attachments: MAPREDUCE-1304.patch
>
>
> It's easy to grab the number of millis spent in GC (see JvmMetrics for example). Exposing these as task counters would be handy - occasionally I've seen user jobs where long GC pauses cause big "unexplainable" performance problems, and a large counter would make it obvious to the user what's going on.

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