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https://issues.apache.org/jira/browse/HADOOP-2119?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12566316#action_12566316
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Owen O'Malley commented on HADOOP-2119:
---------------------------------------

{quote}
On a cache miss, if you don't mind returning a virgin task ahead of a failed 
task,
{quote}
This is unacceptable. We used to have this behavior and it was very bad. If map 
0 fails deterministically, you absolutely do not want all 200,000 maps to fail 
4 times each before the job fails.

> JobTracker becomes non-responsive if the task trackers finish task too fast
> ---------------------------------------------------------------------------
>
>                 Key: HADOOP-2119
>                 URL: https://issues.apache.org/jira/browse/HADOOP-2119
>             Project: Hadoop Core
>          Issue Type: Bug
>          Components: mapred
>    Affects Versions: 0.16.0
>            Reporter: Runping Qi
>            Assignee: Amar Kamat
>            Priority: Critical
>             Fix For: 0.17.0
>
>         Attachments: hadoop-2119.patch, hadoop-jobtracker-thread-dump.txt
>
>
> I ran a job with 0 reducer on a cluster with 390 nodes.
> The mappers ran very fast.
> The jobtracker lacks behind on committing completed mapper tasks.
> The number of running mappers displayed on web UI getting bigger and bigger.
> The jos tracker eventually stopped responding to web UI.
> No progress is reported afterwards.
> Job tracker is running on a separate node.
> The job tracker process consumed 100% cpu, with vm size 1.01g (reach the heap 
> space limit).

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