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Date: Thu, 11 May 2017 22:11:04 +0000 (UTC)
From: "Jason Lowe (JIRA)" <jira@apache.org>
To: yarn-issues@hadoop.apache.org
Message-ID: <JIRA.12850485.1438309492000.192428.1494540664336@Atlassian.JIRA>
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References: <JIRA.12850485.1438309492000@Atlassian.JIRA> <JIRA.12850485.1438309492917@jira-lw-us.apache.org>
Subject: [jira] [Commented] (YARN-4002) make
 ResourceTrackerService.nodeHeartbeat more concurrent
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archived-at: Thu, 11 May 2017 22:11:09 -0000


    [ https://issues.apache.org/jira/browse/YARN-4002?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16007289#comment-16007289 ] 

Jason Lowe commented on YARN-4002:
----------------------------------

FYI we're finding this change to be quite expensive on large clusters.  See HADOOP-14412.

> make ResourceTrackerService.nodeHeartbeat more concurrent
> ---------------------------------------------------------
>
>                 Key: YARN-4002
>                 URL: https://issues.apache.org/jira/browse/YARN-4002
>             Project: Hadoop YARN
>          Issue Type: Improvement
>            Reporter: Hong Zhiguo
>            Assignee: Hong Zhiguo
>            Priority: Critical
>             Fix For: 2.8.0, 3.0.0-alpha1
>
>         Attachments: 0001-YARN-4002.patch, YARN-4002-lockless-read.patch, YARN-4002-rwlock.patch, YARN-4002-rwlock-v2.patch, YARN-4002-rwlock-v2.patch, YARN-4002-rwlock-v3.patch, YARN-4002-rwlock-v3-rebase.patch, YARN-4002-rwlock-v4.patch, YARN-4002-rwlock-v5.patch, YARN-4002-rwlock-v6.patch, YARN-4002-v0.patch
>
>
> We have multiple RPC threads to handle NodeHeartbeatRequest from NMs. By design the method ResourceTrackerService.nodeHeartbeat should be concurrent enough to scale for large clusters.
> But we have a "BIG" lock in NodesListManager.isValidNode which I think it's unnecessary.
> First, the fields "includes" and "excludes" of HostsFileReader are only updated on "refresh nodes".  All RPC threads handling node heartbeats are only readers.  So RWLock could be used to  alow concurrent access by RPC threads.
> Second, since he fields "includes" and "excludes" of HostsFileReader are always updated by "reference assignment", which is atomic in Java, the reader side lock could just be skipped.


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