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https://issues.apache.org/jira/browse/SPARK-2468?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14202056#comment-14202056
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Lianhui Wang edited comment on SPARK-2468 at 11/7/14 2:01 PM:
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[~adav]  yes,with https://github.com/apache/spark/pull/3155/  in my test  
beyond physical memory limits does not happened.but i discover that Netty's 
performance is not good than NioBlockTransferService. so I need to find why 
Netty's performance is bad than NioBlockTransferService in my test.Can you give 
me some suggestions? thanks.and how about your test? [~zzcclp]


was (Author: lianhuiwang):
[~adav]  yes,with https://github.com/apache/spark/pull/3155/  in my test  it 
does not happened.but i discover that Netty's performance is not good than 
NioBlockTransferService. so I need to find why Netty's performance is bad than 
NioBlockTransferService in my test.Can you give me some suggestions? thanks.and 
how about your test? [~zzcclp]

> 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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