[
https://issues.apache.org/jira/browse/HDFS-14162?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16740767#comment-16740767
]
Erik Krogen commented on HDFS-14162:
------------------------------------
Thanks for looking [~shv]. Unfortunately, not quite. Let's take
{{BalancerProtocol extends NamenodeProtocol, ClientProtocol}} as an example.
The underlying proxies are of type {{NamenodeProtocolPB}} and
{{ClientProtocolPB}}, classes autogenerated by Protobuf. If we do like:
{code}newProxyInstance(..., new Class[] { NamenodeProtocolPB.class,
ClientProtocolPB.class }, ... {code}
we get back a proxy which is both a {{NamenodeProtocolPB}} and a
{{ClientProtocolPB}}. Now how do we translate this into a {{BalancerProtocol}}?
We would need to write a {{BalancerProtocolTranslatorPB}} which takes in an
object, verifies it is both a {{NamenodeProtocolPB}} and a
{{ClientProtocolPB}}, and then delegates the translation to the relevant
translator... So the same type of delegation I'm doing now, but it took a lot
more work to achieve it.
Alternatively, we could define a new {{BalancerProtocol.proto}} and then
instantiate a proxy of type {{BalancerProtocolPB}}. Unfortunately Protobuf
services don't support inheritance, so we would have to copy-paste all of the
{{rpc}} definitions from both of the other proto files, and we're still left
with the problem of how to deal with the translator.
> Balancer should work with ObserverNode
> --------------------------------------
>
> Key: HDFS-14162
> URL: https://issues.apache.org/jira/browse/HDFS-14162
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Reporter: Konstantin Shvachko
> Assignee: Erik Krogen
> Priority: Major
> Attachments: HDFS-14162-HDFS-12943.wip0.patch, HDFS-14162.000.patch,
> testBalancerWithObserver.patch
>
>
> Balancer provides a substantial RPC load on NameNode. It would be good to
> divert Balancer RPCs {{getBlocks()}}, etc. to ObserverNode. The main problem
> is that Balancer uses {{NamenodeProtocol}}, while ORPP currently supports
> only {{ClientProtocol}}.
--
This message was sent by Atlassian JIRA
(v7.6.3#76005)
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
