[jira] [Updated] (HDFS-918) Use single Selector and small thread pool to replace many instances of BlockSender for reads

["Todd Lipcon (Updated) (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HDFS-918?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Todd Lipcon updated HDFS-918:
-----------------------------

    Component/s: performance
    
> Use single Selector and small thread pool to replace many instances of BlockSender for reads
> --------------------------------------------------------------------------------------------
>
>                 Key: HDFS-918
>                 URL: https://issues.apache.org/jira/browse/HDFS-918
>             Project: Hadoop HDFS
>          Issue Type: Improvement
>          Components: data-node, performance
>            Reporter: Jay Booth
>            Assignee: Jay Booth
>         Attachments: hbase-hdfs-benchmarks.ods, hdfs-918-20100201.patch, hdfs-918-20100203.patch, hdfs-918-20100211.patch, hdfs-918-20100228.patch, hdfs-918-20100309.patch, hdfs-918-TRUNK.patch, hdfs-918-branch20-append.patch, hdfs-918-branch20.2.patch, hdfs-918-pool.patch, hdfs-multiplex.patch
>
>
> Currently, on read requests, the DataXCeiver server allocates a new thread per request, which must allocate its own buffers and leads to higher-than-optimal CPU and memory usage by the sending threads.  If we had a single selector and a small threadpool to multiplex request packets, we could theoretically achieve higher performance while taking up fewer resources and leaving more CPU on datanodes available for mapred, hbase or whatever.  This can be done without changing any wire protocols.

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