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https://issues.apache.org/jira/browse/HADOOP-9151?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13536380#comment-13536380
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Sanjay Radia commented on HADOOP-9151:
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Binglin, you are suggesting to merge the rpc-request body inside the
RpcRequestHeader and the rpc-repsponse body inside RpcResponseHeader. You are
right in that we could add a bytes field to each of the headers and that it
would not break the Multiple rpc engine abstraction.
Generally it is better to keep the distinct "messages" distinct, each
length-deliminated. The Protobuf rpc messages of the various RPC services get
generated independently anyway. As far as efficiency there are two separate
issues.
# wire packets - we are writing data into a tcp stream via a bufferOutputStream
and so there should be no difference.
# internal buffers - indeed putting the body inside the header can cause extra
copying depending on how you write your code. A further note on internal data
copying: our rpc code should be changed to use CodeOutputStream to minimize
data copying; I will file a jira for that.
While I was changing the code, I noticed that the ProtobufRpcEngine.proto
includes the rpc message inside the header and indeed that will force extra
copying and in my opinion should have been kept distinct.
> Include RPC error info in RpcResponseHeader instead of sending it separately
> ----------------------------------------------------------------------------
>
> Key: HADOOP-9151
> URL: https://issues.apache.org/jira/browse/HADOOP-9151
> Project: Hadoop Common
> Issue Type: Sub-task
> Reporter: Sanjay Radia
> Assignee: Sanjay Radia
> Attachments: HADOOP-9151.patch
>
>
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