large rails application boot time - ruby-on-rails

Question

I have a very very large rails application and I've read every post there on how to reduce boot time, each suggesting to cut down on models or controllers or gems, but all of them are being used.
Problem i'm facing is that heroku pushes R10 error code since my app takes more than 60s to load.
I've been trying one thing, almost successfully. I'm trying to run Bundler.require and Application.inialize! in threads (latter thread waiting on the first one to finish). Advantage of this being that thin server boots almost instantly.
Problem is, when someone hits the app with a request, the initialization process stays incomplete. Any idea how i can achieve this?

Answer 1

You can take control of the initialization process by extending the initialize! method in config/application.rb.
Look at this sample application.rb file from a github project. You should be able to extend the initialize! method inside of the class Application < Rails::Application scope.
You can take the base methods from the Rails Initialization docs in section 2.3 railties/lib/rails/application.rb. So here is what you'll have if you extend the methods and leave them as they are implemented by default.
class Application < Rails::Application
def initialize!(group=:default) #:nodoc:
raise "Application has been already initialized." if #initialized
run_initializers(group, self)
#initialized = true
self
end
def run_initializers(group=:default, *args)
return if instance_variable_defined?(:#ran)
initializers.tsort_each do |initializer|
initializer.run(*args) if initializer.belongs_to?(group)
end
#ran = true
end
end
At this point you can add print statements and determine which piece you're getting stuck on. For example, is your #initialized variable never being set to true? If so, why? Perhaps you are getting stuck inside of run_intializers. If that is the case, then which initializer are you getting stuck inside of?

Answer 2

I've realized what i'm trying to do is not possible. So i'm ending the thread.
What i'm doing:
In my environment.rb,
def init_bundler
# If you want your assets lazily compiled in production, use this line
s = Time.now
_rails_groups = (ENV["RAILS_GROUPS"]||"").split(",")
if _rails_groups.length == 1 and _rails_groups.first.to_s == "assets"
Bundler.require(:assets) #load ONLY assets ..
elsif _rails_groups.length == 1 and _rails_groups.first.to_s == "clock"
Bundler.require(:clock) #load ONLY assets ..
else
Bundler.require(:default, *_rails_groups, Rails.env.to_s)
end
puts "bundler required in #{Time.now - s}s"
end
puts "starting t1"
$_t1 = Thread.new{ init_bundler }
In my environment.rb:
def init_app
# Initialize the rails application
puts "initialize started"
s = Time.now
Hedgepo::Application.initialize!
puts "initialize done in #{Time.now - s}s"
end
puts "starting t2"
$_t2 = Thread.new do
loop do
if defined?($_t1) and !$_t1.status
init_app
break
else
puts "waiting for bundler"
end
sleep(1)
end
end
the middleware i'm using above everyone else:
class MyInit
def initialize(app)
#app = app
end
def call(env)
loop do
if defined?($_t2) and !$_t2.status
break
else
puts "waiting for app init to finish...."
end
sleep(1)
end
#app.call(env)
end
end
But the problem is that Rack::Server allocates an 'app' variable and .start!s the server when the hit comes. So whatever I do, i cannot change the app that was initialized BEFORE this #app variable was populated.