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https://issues.apache.org/jira/browse/MAPREDUCE-5723?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13878693#comment-13878693
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Jason Lowe commented on MAPREDUCE-5723:
---------------------------------------
Agree with Karthik that a test case would be nice because unit tests are useful
for regression tests and not just for new functionality. However this will be
a bit tricky to test via spy since LogManager.shutdown is a static function,
and MRAppMaster is not invoking it via an object that can be modified for
testing. For this patch I'm OK if it doesn't have a test since it's relatively
small and straightforward, but in general we want unit tests even if it's just
a bugfix.
As for the patch itself, we need to call LogManager.shutdown() after
super.stop(), otherwise we end up shutting down the logging system before
shutting down all the services registered within the MRAppMaster service. We
want to see the logs of those sub-services shutting down.
> MR AM container log empty if exception occurs
> ---------------------------------------------
>
> Key: MAPREDUCE-5723
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-5723
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Components: applicationmaster
> Affects Versions: 2.2.0
> Reporter: Mohammad Kamrul Islam
> Assignee: Mohammad Kamrul Islam
> Fix For: trunk, 2.2.0
>
> Attachments: MAPREDUCE-5723.1.patch, MAPREDUCE-5723.2.patch,
> MAPREDUCE-5723.3.patch
>
>
> It occurs when the property "mapreduce.task.userlog.limit.kb" is set non-zero
> in mapped-site.xml.
> AM container syslog remains empty if any exception occurs.
> Bug details:
> In MRAppMaster.java, the following code snippets show the bug.
> {code}
> } catch (Throwable t) {
> LOG.fatal("Error starting MRAppMaster", t);
> System.exit(1);
> }finally {
> LogManager.shutdown();
> }
> {code}
> In the catch block, we are exiting the JVM. So finally block (therefore
> LogManager.shutdown()) is never executed.
> Possible fix:
> Make sure LogManager.shutdown() is executed in all cases.
>
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