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https://issues.apache.org/jira/browse/MAPREDUCE-220?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12894990#action_12894990
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Scott Chen commented on MAPREDUCE-220:
--------------------------------------

Hey Philip,

We haven't try test this under the case of JVM re-use. But I think you are 
right about this.
We need to do some more work for this case.

We can still get the correct PID in JVM reuse case. Because we use
{code}
String pid = System.getenv().get("JVM_PID");
{code}
which is invoked from Task.updateCounters().
So we should be able to get the correct PID for the task no matter JVM is 
reused or not.

The problem is the cumulated CPU time. Because the process may be used by 
another task for a while.
One way to solve this is to send only the current value instead of cumulated 
value.
Does this sound correct to you?

Scott

> Collecting cpu and memory usage for MapReduce tasks
> ---------------------------------------------------
>
>                 Key: MAPREDUCE-220
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-220
>             Project: Hadoop Map/Reduce
>          Issue Type: New Feature
>          Components: task, tasktracker
>            Reporter: Hong Tang
>            Assignee: Scott Chen
>             Fix For: 0.22.0
>
>         Attachments: MAPREDUCE-220-20100616.txt, MAPREDUCE-220-v1.txt, 
> MAPREDUCE-220.txt
>
>
> It would be nice for TaskTracker to collect cpu and memory usage for 
> individual Map or Reduce tasks over time.

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