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https://issues.apache.org/jira/browse/HADOOP-8292?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13271527#comment-13271527
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Alejandro Abdelnur commented on HADOOP-8292:
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Forgot to mention, I'm using a daemon thread with a while(true) loop because
the DNSToSwitchMapping interface does not have lifecycle methods (init/destroy)
I could use to shutdown the thread. This could be done, but I'd argue as part
of another JIRA
> TableMapping does not refresh when topology is updated
> ------------------------------------------------------
>
> Key: HADOOP-8292
> URL: https://issues.apache.org/jira/browse/HADOOP-8292
> Project: Hadoop Common
> Issue Type: Bug
> Affects Versions: 2.0.0
> Reporter: Philip Zeyliger
> Assignee: Alejandro Abdelnur
> Attachments: HADOOP-8292.patch, HADOOP-8292.patch
>
>
> HADOOP-7030 introduced TableMapping, an implementation of DNSToSwitchMapping
> which uses a file to map from IPs/hosts to their racks. It's intended to
> replace ScriptBasedMapping for cases where the latter was just a complicated
> way of looking up the rack in a file.
> Though there was discussion of it on the JIRA, the TableMapping
> implementation is not 'refreshable'. i.e., if you want to add a host to your
> cluster, and that host wasn't in the topology file to begin with, it will
> never be added.
> TableMapping should refresh, either based on a command that can be executed,
> or, perhaps, if the file on disk changes.
> I'll also point out that TableMapping extends CachedDNSToSwitchMapping, but,
> since it does no refreshing, I don't see what the caching gets you: I think
> the cache ends up being a second copy of the underlying map, always.
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