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https://issues.apache.org/jira/browse/MAPREDUCE-5694?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13877635#comment-13877635
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Jason Lowe commented on MAPREDUCE-5694:
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I recently noticed that AM logs were being truncated, see MAPREDUCE-5730, and
it appears to be caused by this change. The patch is shutting down the
LogManager in the finally block of the main thread, but the main method does
not wait around for the MRAppMaster to complete. This means under normal
conditions the log system is being shutdown sometime shortly after startup,
effectively disabling the AM logs entirely after that point.
> MR AM container syslog is empty
> ---------------------------------
>
> Key: MAPREDUCE-5694
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-5694
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Affects Versions: 2.2.0
> Reporter: Mohammad Kamrul Islam
> Assignee: Mohammad Kamrul Islam
> Fix For: 2.4.0
>
> Attachments: MAPREDUCE-5694.1.patch
>
>
> When the property "mapreduce.task.userlog.limit.kb" is set non-zero in
> mapped-site.xml, AM container syslog remains empty. Without the log, it is
> hard to identify the cause of any MR AM failure.
> However, if "mapreduce.task.userlog.limit.kb" is not set (or defaulted to
> 0), syslog contents are correct.
>
> Bug details:
> For non zero "mapreduce.task.userlog.limit.kb", the code caches the log
> contents into memory, waited to be written to file when close() method is
> called at the end(Ref: ContainerLogAppender.java).
> Explicit call of LogManager.shutdown() from the main()
> (REF:MRAppMaster.java), ultimately call the *Appender.close().
> Root Cause:
> LogManager.shutdown() is not being called from MRAppMaster.java.
> Similar steps were taken correctly in YarnChild.java.
>
>
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