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https://issues.apache.org/jira/browse/HADOOP-2119?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12580969#action_12580969
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Owen O'Malley commented on HADOOP-2119:
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In the JobTracker:
* siblingSetAtLevel seems really arcane. I would propose that instead you add
getChildren to the Node interface.
* why is there yet another map from hostname to Node? This is already done in
the node mapping.
In the JobInProgress:
* I'm really concerned that we are adding 5 new fields holding collections to
the JobInProgress
* reducers is a really bad name. I'd suggest runnableReduces or something.
* nodesToMaps should be runnableMaps
* Don't use assignment in a parameter to a method in initTasks
* I'm bothered by all of the checks for null Nodes that just skip the
location. I think it should be a warn in the job tracker logs so that admins
can find the problem and should be the default node/ default rack.
* Shouldn't we remove the node from the nodesToMaps regardless of the level?
Since if it is running, it is also in the runningMaps list and we can speculate
out of there.
* nodesToMaps being null should be a fatal error
* nodesToMaps should be a Map<Node,Set<Tip>> rather than a list of tips, so
that we can remove things reasonably fast
i'll look some more tonight.
> 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-v4.1.patch, HADOOP-2119-v5.1.patch,
> HADOOP-2119-v5.1.patch, 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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