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https://issues.apache.org/jira/browse/HDFS-918?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12976853#action_12976853
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Todd Lipcon commented on HDFS-918:
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bq. When you say we could get it into 0.23, you thinking all of it or just some
pieces of this patch?
I only looked at the ReadChannel pool bit so far. Let's do one thing at a time
;-) If we get that in, no reason we can't move on to the next bit. Like I said
above, for the more "scary" changes, I think it's important that we give some
config flag to enable/disable the new behavior where we can.
> 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
> Reporter: Jay Booth
> Assignee: Jay Booth
> Fix For: 0.22.0
>
> 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-branch20-append.patch,
> hdfs-918-branch20.2.patch, hdfs-918-pool.patch, hdfs-918-TRUNK.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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