I recently had a chance to play around with EventMachine, as I wanted to set up an event-based scheduler within my application. I was not impressed. If you tr

I recently had a chance to play around with EventMachine, as I wanted to set up an event-based scheduler within my application. I was not impressed. If you try and mix 'EventMachine' and 'other threadsafe code', it seems to fall down pretty hard. In my case, it would run anything executed via next_tick, but would refuse to run any timers... unless I defined a periodic timer in the main event loop, after which timers started working... but only every time the periodic timer executed. I dug through the code to see if I could fix the problem, and gave up after trying to figure out why they seem to implement timers in two different ways, and it doesn't seem very threadsafe (next_tick is, but none of the timer code looks to be). EM also expects that your entire application will run inside the EventMachine loop; there's no way to ask EM for a Reactor that you can then hand events. If you're not running threaded code, then EM will probably work just fine; the Thin webserver looks to be a really nice Rack deployment option if you're on MRI. If you need to mix EM up with anything else running on the same VM, look elsewhere.