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Posted to hdfs-issues@hadoop.apache.org by "Konstantin Shvachko (Jira)" <ji...@apache.org> on 2020/04/21 02:04:00 UTC

[jira] [Updated] (HDFS-15291) [SBN read] Implement CyclicalBlockingQueue to avoid requing RPC calls on Observer.

     [ https://issues.apache.org/jira/browse/HDFS-15291?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Konstantin Shvachko updated HDFS-15291:
---------------------------------------
    Description: 
RPC queue is currently based on {{LinkedBlockingQueue}}, which is FIFO.
For Observer we delay execution of a call if its lastSeenStateId is larger than the stateId of the Observer. The delay implemented as re-queuing the call to the end of the queue. Re-queue is not atomic. We can avoid moving elements in the queue by replacing {{LinkedBlockingQueue}} with a {{CyclicalBlockingQueue}}. So that instead of re-queuing we just move the head of the queue and the call automatically becomes the last.

  was:
RPC queue is currently based on {{LinkedBlockingQueue}}, which is FIFO.
For Observer we delay execution of a call if its lastSeenStateId is larger than the stateId of the Observer. The delay implemented as re-queuing the call to the and of the queue. Re-queue is not atomic. We can avoid moving elements in the queue by replacing {{LinkedBlockingQueue}} with a {{CyclicalBlockingQueue}}. So that instead of re-queuing we just move the head of the queue and the call automatically becomes the last.


> [SBN read] Implement CyclicalBlockingQueue to avoid requing RPC calls on Observer.
> ----------------------------------------------------------------------------------
>
>                 Key: HDFS-15291
>                 URL: https://issues.apache.org/jira/browse/HDFS-15291
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>          Components: namenode
>            Reporter: Konstantin Shvachko
>            Priority: Major
>
> RPC queue is currently based on {{LinkedBlockingQueue}}, which is FIFO.
> For Observer we delay execution of a call if its lastSeenStateId is larger than the stateId of the Observer. The delay implemented as re-queuing the call to the end of the queue. Re-queue is not atomic. We can avoid moving elements in the queue by replacing {{LinkedBlockingQueue}} with a {{CyclicalBlockingQueue}}. So that instead of re-queuing we just move the head of the queue and the call automatically becomes the last.



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