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https://issues.apache.org/jira/browse/HADOOP-12321?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14743207#comment-14743207
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Steve Loughran commented on HADOOP-12321:
-----------------------------------------
Its maven race conditions surfacing —if there is >1 simultaneous build then the
artifacts may not be synchronized. Looks like a hadoop-common JAR from a
different build was picked up.
The test failures in MAPREDUCE-6462 *are* related.
They are easy to fix; if you do that then you can resubmit the entire patch
under all three JIRAs as I did, so as to get the builds and tests across all
the components
> Make JvmPauseMonitor to AbstractService
> ---------------------------------------
>
> Key: HADOOP-12321
> URL: https://issues.apache.org/jira/browse/HADOOP-12321
> Project: Hadoop Common
> Issue Type: New Feature
> Affects Versions: 2.8.0
> Reporter: Steve Loughran
> Assignee: Sunil G
> Attachments: 0001-HADOOP-12321.patch, 0002-HADOOP-12321.patch,
> HADOOP-12321-003.patch
>
> Original Estimate: 1h
> Remaining Estimate: 1h
>
> The new JVM pause monitor has been written with its own start/stop lifecycle
> which has already proven brittle to both ordering of operations and, even
> after HADOOP-12313, is not thread safe (both start and stop are potentially
> re-entrant).
> It also requires every class which supports the monitor to add another field
> and perform the lifecycle operations in its own lifecycle, which, for all
> Yarn services, is the YARN app lifecycle (as implemented in Hadoop common)
> Making the monitor a subclass of {{AbstractService}} and moving the
> init/start & stop operations in {{serviceInit()}}, {{serviceStart()}} &
> {{serviceStop()}} methods will fix the concurrency and state model issues,
> and make it trivial to add as a child to any YARN service which subclasses
> {{CompositeService}} (most the NM and RM apps) will be able to hook up the
> monitor simply by creating one in the ctor and adding it as a child.
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