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https://issues.apache.org/jira/browse/SPARK-2468?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14201754#comment-14201754
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Lianhui Wang commented on SPARK-2468:
-------------------------------------

[~adav] when i set the spark config "spark.shuffle.io.preferDirectBufs=false", 
and yarn still kill executor's container because it's physical memory beyond 
allocated memory.so i think netty have used big no-heap jvm memory.

> 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
>             Fix For: 1.2.0
>
>
> 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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