lmarburger/metriks-middleware — pull request #1 by indirect (2012-12-11 22:18:21+00:00)
Title: Track number of dynos in use

This just adds one extra metric to track the (Heroku-reported) number of dynos in use when the request was processed. This metric can give you a pretty good idea if your app is over-provisioned (just like the queue length metric can give you a pretty good idea that you're under-provisioned.)