I think there's really two angles to look at this from...

1) What is 'important' to monitor?  Meaning, what subset of these are
important/critical for being able to tell system health (things you want
to set alerts on), what subset are nice to have for overall health and
capacity planning (things you want to create pretty graphs on) and the
rest (not immediately useful in general, but can really help in a
debugging/triage situation).

2) How do you get the data?  Kind of independent of the above, though
kinda related as well.  

As for the second one, you need to look at the collection mechanics.  As
you mentioned below, large scale polling (especially with a non-trivial
number of beans) is expensive and problematic no matter how you do it
(JMX or HTTP) given enough scale.  I don't have much experience with the
codahale metrics route directly, but I have messed with Jolokia, which is
likely in the same boat - they expose the metrics for you to grab. In
both cases, given enough data points (and kafka, depending on the number
of topics involved, has a /lot/ of them), either can be slow if not
implemented carefully.  Meaning you may overrun your desired polling

In very large environments, I've found it very scalable to have either a
local poller on the box (which could be reading via JMX or HTTP) which
then emits the data to something or have some kind of wrapper around the
application that does the collection/emission (launching the broker as a
thread, and the parent process dows some JMX magic to connect to the
data points).  Both of these routes depend a lot on your monitoring
infrastructure, but they will help you get around the general wide
polling problem...

Semi-shameless plug for how it is done at LinkedIn - http://engineering.linkedin.com/52/autometrics-self-service-metrics-collection

Dave DeMaagd
[EMAIL PROTECTED] | 818 262 7958

([EMAIL PROTECTED] - Wed, May 08, 2013 at 09:27:21PM +0000)
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