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https://issues.apache.org/jira/browse/YARN-4946?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16567434#comment-16567434
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Robert Kanter commented on YARN-4946:
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I'm not sure if any of the 3 versions of the ATS have the log aggregation
status info. But I agree that we shouldn't add this dependency if possible. I
also think it makes sense for the RM to remember Applications if they're still
doing something, including the log aggregation.
Thanks for the patch [~snemeth], a couple things:
# I'm not sure creating so many helper methods is necessary, especially the
ones that are one or two lines of code like {{recordLogAggregationStartTime}}.
# The current approach is changing when an App is considered finished
({{APP_COMPLETED}}) and delaying it until the log aggregation has finished.
That could take minutes after the App actually finishes, so this is going to
add a considerable delay on a bunch of other things - definitely something
users will notice. I think we should try to limit the scope of the changes so
that we leave the App lifecycle as-is, but only change the part where we decide
to evict an App from the RM.
#- More specifically, if you look at
{{RMAppManager#checkAppNumCompletedLimit}}, you can see that it's comparing a
counter for the number of completed apps vs the configured max. We can simply
adjust the logic here or the counter to only count an App once it's both
completed _and_ log aggregation has completed.
> RM should not consider an application as COMPLETED when log aggregation is
> not in a terminal state
> --------------------------------------------------------------------------------------------------
>
> Key: YARN-4946
> URL: https://issues.apache.org/jira/browse/YARN-4946
> Project: Hadoop YARN
> Issue Type: Improvement
> Components: log-aggregation
> Affects Versions: 2.8.0
> Reporter: Robert Kanter
> Assignee: Szilard Nemeth
> Priority: Major
> Attachments: YARN-4946.001.patch, YARN-4946.002.patch
>
>
> MAPREDUCE-6415 added a tool that combines the aggregated log files for each
> Yarn App into a HAR file. When run, it seeds the list by looking at the
> aggregated logs directory, and then filters out ineligible apps. One of the
> criteria involves checking with the RM that an Application's log aggregation
> status is not still running and has not failed. When the RM "forgets" about
> an older completed Application (e.g. RM failover, enough time has passed,
> etc), the tool won't find the Application in the RM and will just assume that
> its log aggregation succeeded, even if it actually failed or is still running.
> We can solve this problem by doing the following:
> The RM should not consider an app to be fully completed (and thus removed
> from its history) until the aggregation status has reached a terminal state
> (e.g. SUCCEEDED, FAILED, TIME_OUT).
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