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https://issues.apache.org/jira/browse/YARN-2923?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14396106#comment-14396106
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Jian Fang commented on YARN-2923:
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Thanks Naganarasimha for your reply.
I think the watcher API is different from your polling mechanism. I guess it
probably uses the Linux inotify mechanism under the hood and the polling only
gets back the results from inotify. That could mean the watcher does not
actually check the filesystem for each poll. I am not familiar with Java source
code and this is only my guess. Here is a discussion on DZone:
http://java.dzone.com/news/how-watch-file-system-changes.
The reason I mentioned HADOOP-7001 is that configuration update is very common
in cloud since nodes in a hadoop cluster are ephemeral and could be gone. I
know HADOOP-7001 defined some interfaces, but am not aware of its current
progress. It would be great if the whole Hadoop project could use the same
mechanism to handle configuration updates for different use cases. Does that
make sense?
> Support configuration based NodeLabelsProvider Service in Distributed Node
> Label Configuration Setup
> -----------------------------------------------------------------------------------------------------
>
> Key: YARN-2923
> URL: https://issues.apache.org/jira/browse/YARN-2923
> Project: Hadoop YARN
> Issue Type: Sub-task
> Components: nodemanager
> Reporter: Naganarasimha G R
> Assignee: Naganarasimha G R
> Fix For: 2.8.0
>
> Attachments: YARN-2923.20141204-1.patch, YARN-2923.20141210-1.patch,
> YARN-2923.20150328-1.patch, YARN-2923.20150404-1.patch
>
>
> As part of Distributed Node Labels configuration we need to support Node
> labels to be configured in Yarn-site.xml. And on modification of Node Labels
> configuration in yarn-site.xml, NM should be able to get modified Node labels
> from this NodeLabelsprovider service without NM restart
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