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https://issues.apache.org/jira/browse/YARN-4002?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15288564#comment-15288564
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Rohith Sharma K S commented on YARN-4002:
-----------------------------------------

bq. also, setExcludesFile, setIncludesFile, updateFileNames need not acquire 
the writelock or can they just be removed ?
I see class is annotated with limited private which are with in the hadoop 
project only. But still I feel since it util method in hadoop-common may be any 
other projects might be used. Should it still get removed?

> 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
>         Attachments: 0001-YARN-4002.patch, YARN-4002-lockless-read.patch, 
> YARN-4002-rwlock-v2.patch, YARN-4002-rwlock-v2.patch, 
> YARN-4002-rwlock-v3-rebase.patch, YARN-4002-rwlock-v3.patch, 
> YARN-4002-rwlock-v4.patch, YARN-4002-rwlock-v5.patch, YARN-4002-rwlock.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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