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https://issues.apache.org/jira/browse/HADOOP-5478?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12720185#action_12720185
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Hong Tang commented on HADOOP-5478:
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bq Hong, is this to check if the TT is alive ? In which case, did you mean
another signal, like -0 or kill -3. -9 is SIGKILL and would kill the TT. Also,
in that case are you suggesting that we could keep the health checker around
and continue trying to report after a while ?
@hemanth sorry for not being clear. I gave a bit more thoughts on the problem,
and I think the following logic may be simpler and more robust (1,2 are the
current logic, 3 is my suggestion) :
(1) periodically launch the health checking script;
(2) reporting status that back to TT (both good and bad);
(3) if it fails to receive response from TT, wait for X seconds, do an extra
kill (to ensure TT is dead), and quit itself.
I scanned through the code, it seems that NodeHealthChecker.stop() would be a
good place to perform step (3).
> Provide a node health check script and run it periodically to check the node
> health status
> ------------------------------------------------------------------------------------------
>
> Key: HADOOP-5478
> URL: https://issues.apache.org/jira/browse/HADOOP-5478
> Project: Hadoop Core
> Issue Type: New Feature
> Components: mapred
> Affects Versions: 0.20.0
> Reporter: Aroop Maliakkal
> Assignee: Sreekanth Ramakrishnan
> Attachments: hadoop-5478-1.patch, hadoop-5478-2.patch,
> hadoop-5478-3.patch, hadoop-5478-4.patch, hadoop-5478-5.patch
>
>
> Hadoop must have some mechanism to find the health status of a node . It
> should run the health check script periodically and if there is any errors,
> it should black list the node. This will be really helpful when we run static
> mapred clusters. Else we may have to run some scripts/daemons periodically to
> find the node status and take it offline manually.
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