AAaarongough·Jun 7, 2010
I didn't go with Rails 3, I like to keep at least a minor version behind so I don't have to deal with framework bugs in production :-p
In my case the performance issues really have nothing to do with Rails and everything to do with blocking I/O. Rails 3 and Ruby 1.9 may be faster, but that doesn't help you at all if you do something like this:
class ExampleController < ActionController::Base
def index
sleep(1) # contrived example, imagine a slow API call here
render :text => "Completed!"
end
end
Because Rails is setup to be run in a blocking fashion my example will only be able to serve 1 request per second. The fix here is non-blocking languages (like Node.js) or programming in an event-driven fashion (by using EventMachine or the like). For example (in pseudocode):
when( request.received ) do
register slow
Read the rest
_api_request, :callback => :answer
end
def answer do
response.send( api_result )
end
Ideally the framework should do this by itself. Standard libraries that are blocking, like Net:Http, should continue to appear to the developer like they are blocking, but in reality would pass back control to other instructions while they're just sitting around waiting for the remote server to respond.
This is totally possible, and getting more feasible by the day. Thin (the application server) and Rack both allow applications to run asynchronously, Neverblock provides a cleaner way for providing pools of Ruby Fibers to an application to allow implicit scheduling, in time Rails will hopefully build upon this. I've spent several hours this morning doing research into how I can fix this problem for my application, some of the stuff I've dug-up is here:
http://github.com/igrigorik/em-http-request
http://github.com/rkh/async-rack
http://www.espace.com.eg/neverblock/
http://macournoyer.com/blog/2009/06/04/pusher-and-async-with-thin/
It looks like the solution in my case is going to be something like creating a Rails Metal endpoint for Rack, that completes the Net:Http requests using em-http-request. I'm not sure that this is actually possible yet, but it'll be something close to that.