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https://issues.apache.org/jira/browse/HADOOP-12321?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15044895#comment-15044895
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Sunil G commented on HADOOP-12321:
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Yes, the idea sounds perfect. A single revert will really help in case of any
major issues.
> Make JvmPauseMonitor an 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
> Fix For: 2.9.0
>
> Attachments: 0001-HADOOP-12321.patch, 0002-HADOOP-12321.patch,
> 0004-HADOOP-12321.patch, HADOOP-12321-003.patch,
> HADOOP-12321-005-aggregated.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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