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Date: Mon, 26 Sep 2016 12:02:20 +0000 (UTC)
From: "Sunil G (JIRA)" <jira@apache.org>
To: common-issues@hadoop.apache.org
Message-ID: <JIRA.12855767.1439441923000.662450.1474891340819@Atlassian.JIRA>
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References: <JIRA.12855767.1439441923000@Atlassian.JIRA> <JIRA.12855767.1439441923361@arcas>
Subject: [jira] [Commented] (HADOOP-12321) Make JvmPauseMonitor an
 AbstractService
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archived-at: Mon, 26 Sep 2016 12:02:27 -0000


    [ https://issues.apache.org/jira/browse/HADOOP-12321?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15522851#comment-15522851 ] 

Sunil G commented on HADOOP-12321:
----------------------------------

HI [~brahmareddy]

As discussed [here|https://issues.apache.org/jira/browse/MAPREDUCE-6462?focusedCommentId=14743205&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-14743205] , there were no added advantage to count the number of children for a service. hence it was removed. Any 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, 3.0.0-alpha1
>
>         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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