I'm wondering, does this do it's own polling? Or does it just calculate the metric on-demand when the MXBean is accessed?

Also, on the Metrics website, there is a fairly large warning saying not to use this in production:
http://metrics.codahale.com/manual/core/#jmx

Unless we have a firm understanding of what this does internally, it might be good to not enable it by default. Do you know what that warning is about?