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https://issues.apache.org/jira/browse/YARN-4882?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15218340#comment-15218340
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Jason Lowe commented on YARN-4882:
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The problem with saying we can up the log level to DEBUG is that debugging
recovery will often be a postmortem process, trying to figure out why a
particular application wasn't recovered or didn't end up in the right state.
That also means logging a single rollup value for all apps is going to not be
very helpful when the problem is trying to figure out what happened to a
particular app. By the time one wants to re-run the scenario with DEBUG turned
on the state store is going to be significantly different.
I agree the amount of logging is a bit excessive today and can be reduced, but
I also think it's important to track how active applications were recovered. I
can think of a couple of potential options:
1) Reduce the logging for completed applications, potentially just one line per
app or just a rollup number of completed apps. Completed applications dominate
the current recovery logging and are less interesting. For debugging, one can
presume that an app that wasn't logged during recovery either was missing from
the state store or was recovered as completed.
2) Use a separate logger for recovery activity which allows users to control
the amount of logging pertaining to recovery (i.e.: via log level) and
potentially use a separate log file just for recovery
And of course we could do some combination of the above options, both reducing
the recovery logging we have today and allowing the user to control it
separately from normal RM logging.
> Change the log level to DEBUG for recovering completed applications
> -------------------------------------------------------------------
>
> Key: YARN-4882
> URL: https://issues.apache.org/jira/browse/YARN-4882
> Project: Hadoop YARN
> Issue Type: Bug
> Components: resourcemanager
> Reporter: Rohith Sharma K S
> Assignee: Daniel Templeton
>
> I think for recovering completed applications no need to log as INFO, rather
> it can be made it as DEBUG. The problem seen from large cluster is if any
> issue happens during RM start up and continuously switching , then RM logs
> are filled with most with recovering applications only.
> There are 6 lines are logged for 1 applications as I shown in below logs,
> then consider RM default value for max-completed applications is 10K. So for
> each switch 10K*6=60K lines will be added which is not useful I feel.
> {noformat}
> 2016-03-01 10:20:59,077 INFO
> org.apache.hadoop.yarn.server.resourcemanager.RMAppManager: Default priority
> level is set to application:application_1456298208485_21507
> 2016-03-01 10:20:59,094 INFO
> org.apache.hadoop.yarn.server.resourcemanager.rmapp.RMAppImpl: Recovering
> app: application_1456298208485_21507 with 1 attempts and final state =
> FINISHED
> 2016-03-01 10:20:59,100 INFO
> org.apache.hadoop.yarn.server.resourcemanager.rmapp.attempt.RMAppAttemptImpl:
> Recovering attempt: appattempt_1456298208485_21507_000001 with final state:
> FINISHED
> 2016-03-01 10:20:59,107 INFO
> org.apache.hadoop.yarn.server.resourcemanager.rmapp.attempt.RMAppAttemptImpl:
> appattempt_1456298208485_21507_000001 State change from NEW to FINISHED
> 2016-03-01 10:20:59,111 INFO
> org.apache.hadoop.yarn.server.resourcemanager.rmapp.RMAppImpl:
> application_1456298208485_21507 State change from NEW to FINISHED
> 2016-03-01 10:20:59,112 INFO
> org.apache.hadoop.yarn.server.resourcemanager.RMAuditLogger: USER=rohith
> OPERATION=Application Finished - Succeeded TARGET=RMAppManager
> RESULT=SUCCESS APPID=application_1456298208485_21507
> {noformat}
> The main problem is missing important information's from the logs before RM
> unstable. Even though log roll back is 50 or 100, in a short period all these
> logs will be rolled out and all the logs contains only RM switching
> information that too recovering applications!!.
> I suggest at least completed applications recovery should be logged as DEBUG.
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