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From "Withers, Robert" <Robert.With...@dish.com>
Subject RE: one consumerConnector or many?
Date Wed, 29 May 2013 13:53:58 GMT
Thanks for the info.  Are you saying that even with a single connector, with say 3 topics and
3 threads per topic and 3 brokers with 3 partitions for all 3 topics on all 3 brokers, that
a consumer box would have 9 sockets open?  What if there are 6 partitions per topic, would
that be 18 open sockets?

I have read somewhere that a high partition number, per topic, is desirable, to scale out
the consumers and to be prepared to dynamically scale out consumption during a traffic spike.
 Is it so?  100 topics, with 16 brokers and 200 partitions per topic with 1 consumer connector
(just hypothetically so) would be 1600 sockets or 20000 sockets?

For sure these boxes have plenty of ports.  I am just thinking through possible failures and
what flexibility we have in configuration of producers/consumers to topics.  Really the question
is best practices in this area.  A producer server handling 100+ msg types could also connect
quite a bit.  So, perhaps it is best to restrict producer and consumer servers to process
a restricted "class" of types.  Certainly if the producer is also hosting a web server, but
perhaps not as dire on the consumer side.

thanks,
rob  
________________________________________
From: Chris Curtin [curtin.chris@gmail.com]
Sent: Wednesday, May 29, 2013 7:36 AM
To: users
Subject: Re: one consumerConnector or many?

I'd look at a variation of #2. Can your messages by grouped into a 'class
(for lack of a better term)' that are consumed together? For example a
'class' of 'auditing events' or 'sensor events'. The idea would to then
have a topic for 'class'.

A couple of benefits to this:
- you can define your consumption of a 'class's resources by value. So the
'audit' topic may only get a 2 threaded consumer while the 'sensor' class
gets a 10 threaded consumer.
- you can stop processing a 'class' of messages if you need to without
taking all the consumers off line (Assuming you have different processors
or a way while running to alter your number of threads per topic.)

Since it sounds like you may be frequently adding new message types this
approach also allows you to decide if you want to shutdown only a part of
your processing to add the new code to handle the message.

Finally, why the concern about socket use? A well configured Windows or
Linux machine can have thousands of open sockets without problems. Since
0.8.0 only connects to the Broker with the topic/partition you end up with
1 socket per topic/partition and consumer.

Hope this helps,

Chris


On Wed, May 29, 2013 at 9:13 AM, Rob Withers <reefedjib@gmail.com> wrote:

> In thinking about the design of consumption, we have in mind a generic
> consumer server which would consume from more than one message type.  The
> handling of each type of message would be different.  I suppose we could
> have upwards of say 50 different message types, eventually, maybe 100+
> different types.  Which of the following designs would be best and why
> would
> the other options be bad?
>
>
>
> 1)      Have all message types go through one topic and use a dispatcher
> pattern to select the correct handler.  Use one consumerConnector.
>
> 2)      Use a different topic for each message type, but still use one
> consumerConnector and a dispatcher pattern.
>
> 3)      Use a different topic for each message type and have a separate
> consumerConnector for each topic.
>
>
>
> I am struggling with whether my assumptions are correct.  It seems that a
> single connector for a topic would establish one socket to each broker, as
> rebalancing assigns various partitions to that thread.  Option 2 would pull
> messages from more than one topic through a single socket to a particular
> broker, is it so?  Would option 3 be reasonable, establishing upwards of
> 100
> sockets per broker?
>
>
>
> I am guestimating that option 2 is the right way forward, to bound socket
> use, and we'll need to figure out a way to parameterize stream consumption
> with the right handlers for a particular msg type.  If we add a topic, do
> you think we should create a new connector or restart the original
> connector
> with the new topic in the map?
>
>
>
> Thanks,
>
> rob
>
>
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