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https://issues.apache.org/jira/browse/KAFKA-208?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13151884#comment-13151884
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Taylor Gautier commented on KAFKA-208:
--------------------------------------
Jay,
I think I just realized how the solution you proposed in KAFKA-48 can be used
efficiently for my use case. I suppose this was the solution you had proposed
but maybe I did not understand it fully.
If I understand it right, your proposal is that long poll requests can be
pipelined in the server, and once they are satisified they do not stick around,
they should be polled again. So to use my example from above, the way it would
work would be:
-> request messages topic A offset a
-> request messages topic B offset b
-> request messages topic C offset c
(time passes)
<- messages topic B
-> request messages topic B offset b'
(time passes)
-> request messages topic D offset D
(time passes)
<- messages topic C
-> request messages topic C offset c'
etc.
If this is the vision - then let's close this topic and fold it into KAFKA-48 -
I think this will suffice for everything I need.
> Efficient polling mechanism for many topics
> -------------------------------------------
>
> Key: KAFKA-208
> URL: https://issues.apache.org/jira/browse/KAFKA-208
> Project: Kafka
> Issue Type: New Feature
> Reporter: Taylor Gautier
>
> Currently, the way to poll many topics is to submit a request for each one in
> turn, and read the responses. Especially if there are few messages delivered
> on many topics, the network overhead to implement this scheme can far
> outweigh the bandwidth of the actual messages delivered.
> Effectively, for topics A, B, C the request/response scheme is the following:
> -> Request A offset a
> -> Request B offset b
> -> Request C offset c
> <- no messages
> <- 1 message offset b
> <- no messages
> -> Request A offset a
> -> Request B offset b'
> -> Request C offset c
> <- no messages
> <- no messages
> <- no messages
> etc.
> I propose a more efficient mechanism which works a bit like epoll in that the
> client can register interest in a particular topic. There are many options
> for the implementation, but the one I suggest goes like so:
> -> Register interest A offset a
> -> Register interest B offset b
> -> Register interest C offset c
> -> Next message (null)
> <- messages for B (1 message)
> -> Next message (topic B offset b')
> <- no messages
> -> Unregister Interest C
> ...
> It is possible to implement the "Next Message" request as either blocking or
> non-blocking. I suggest that the request format include space for the
> timeout, which if set to 0 will be a nonblocking response, and if set to
> anything other than 0, will block for at most timeout ms.
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