How fast do Heroku workers come up and start crunching? I'd consider porting my worker code to Ruby (right now it's in Clojure) if it meant I could bring it up in seconds.
And they're billed per minute or per second?
And they're billed per minute or per second?
The time it takes to boot a worker mostly depends on your ruby application. The heavier it is, the longer it takes to boot up. Heroku spawns them fast, I think instantly because they are spawned from a compiled slug which is generated each time you push your app to Heroku.
The HireFire checkup interval takes at most 60 seconds, and less if more resources are available on HireFire's servers.
See the HireFireApp homepage's text for more information, or check out it's knowledge base.