This whole we can't optimize for Rails anymore seems like a red herring. Dumb (random) routing is dumb routing. It doesn't matter if you have single threaded Ra

This whole we can't optimize for Rails anymore seems like a red herring. Dumb (random) routing is dumb routing. It doesn't matter if you have single threaded Rails or Django stack or highly concurrent Node.js or Erlang serving requests, if you distribute the requests randomly you're not going to efficiently use your resources and the Heroku "promise" of spinning up a 2nd dyno and getting 100% more concurrency is just not true. All it changes is the details of the analysis, not the core finding. It makes the problem not as worse, but it's still pretty bad, and it's worse the more uneven your traffic is (in terms of how long each request takes to service). All apps, even Unicorn, JRuby, Node.js, Erlang, etc. would benefit from something better than random routing.