[jira] [Commented] (SPARK-2468) Netty-based block server / client module

["Apache Spark (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SPARK-2468?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14094449#comment-14094449 ] 

Apache Spark commented on SPARK-2468:
-------------------------------------

User 'rxin' has created a pull request for this issue:
https://github.com/apache/spark/pull/1907

> Netty-based block server / client module
> ----------------------------------------
>
>                 Key: SPARK-2468
>                 URL: https://issues.apache.org/jira/browse/SPARK-2468
>             Project: Spark
>          Issue Type: Improvement
>          Components: Shuffle, Spark Core
>            Reporter: Reynold Xin
>            Assignee: Reynold Xin
>            Priority: Critical
>
> Right now shuffle send goes through the block manager. This is inefficient because it requires loading a block from disk into a kernel buffer, then into a user space buffer, and then back to a kernel send buffer before it reaches the NIC. It does multiple copies of the data and context switching between kernel/user. It also creates unnecessary buffer in the JVM that increases GC
> Instead, we should use FileChannel.transferTo, which handles this in the kernel space with zero-copy. See http://www.ibm.com/developerworks/library/j-zerocopy/
> One potential solution is to use Netty.  Spark already has a Netty based network module implemented (org.apache.spark.network.netty). However, it lacks some functionality and is turned off by default. 



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