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https://issues.apache.org/jira/browse/HADOOP-9163?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13539751#comment-13539751
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Sanjay Radia commented on HADOOP-9163:
--------------------------------------
Todd, I was planning to change Hadoop rpc to use CodedOutputStream to reduce
copies; this requires no changes in protocol and is merely code change in how
messages are serialized.
However, the nested request field will cause an extra copy.
See HBases's ProtobufRpcCLientEngine#constructRpcRequest
{code}
RpcRequestBody constructRpcRequest(Method method, Object[] params) throws
ServiceException {
RpcRequestBody.Builder builder = RpcRequestBody.newBuilder();
...
param = (Message)params[0];
...
builder.setRequest(param.toByteString());
...
}
{code}
The param.toByteString will cause the rpc request message to be serialized as
bytes. This will be serialized once again when RpcRequestBody is serialized
later. (There is similar code in Hadoop RPC since HBase rpc was copied from
Hadoop rpc as far as I understand.)
Am i mistaken here?
I have tried to see if could have fixed this in a compatible way by setting the
type of Request to be "message" instead of "bytes" as this would not change the
protocol since bytes and message are the same; however I cannot define a field
to be "message" in a .proto file.
Hence my suggesting to move it out. I have not marked this as jira as
incompatible yet since I am still exploring a couple of options.
> The rpc msg in ProtobufRpcEngine.proto should be moved out to avoid an extra
> copy
> ----------------------------------------------------------------------------------
>
> Key: HADOOP-9163
> URL: https://issues.apache.org/jira/browse/HADOOP-9163
> Project: Hadoop Common
> Issue Type: Sub-task
> Reporter: Sanjay Radia
>
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