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https://issues.apache.org/jira/browse/HADOOP-3581?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Vinod Kumar Vavilapalli updated HADOOP-3581:
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Attachment: HADOOP-3581.20080905.txt
bq. In the addTask and removeTask API, the synchonization is not done while
checking for whether tasksToBeAdded and tasksToBeRemoved contain the object or
not. I think this synchronization is required. Because the run method will
access these datastructures and modify them.
We actually don't need these checks, because no where is a task duplicately
added to the data structures in our code. Removing these checks, and attaching
a new patch.
bq. In task cleanup, do we need synchronization when the PID directory is added
to the cleaner thread's queue ?
Not needed. Cleaner thread uses a LinkedBlockingQueue which internally uses
locks.
> Prevent memory intensive user tasks from taking down nodes
> ----------------------------------------------------------
>
> Key: HADOOP-3581
> URL: https://issues.apache.org/jira/browse/HADOOP-3581
> Project: Hadoop Core
> Issue Type: Improvement
> Components: mapred
> Reporter: Hemanth Yamijala
> Assignee: Vinod Kumar Vavilapalli
> Attachments: HADOOP-3581-final.txt, HADOOP-3581.20080901.2.txt,
> HADOOP-3581.20080902.txt, HADOOP-3581.20080904.txt, HADOOP-3581.20080905.txt,
> HADOOP-3581.6.0.txt, patch_3581_0.1.txt, patch_3581_3.3.txt,
> patch_3581_4.3.txt, patch_3581_4.4.txt, patch_3581_5.0.txt, patch_3581_5.2.txt
>
>
> Sometimes user Map/Reduce applications can get extremely memory intensive,
> maybe due to some inadvertent bugs in the user code, or the amount of data
> processed. When this happens, the user tasks start to interfere with the
> proper execution of other processes on the node, including other Hadoop
> daemons like the DataNode and TaskTracker. Thus, the node would become
> unusable for any Hadoop tasks. There should be a way to prevent such tasks
> from bringing down the node.
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