Note: This monkey-patch only works on Rails 2.2

We recently noticed our mongrels, upon startup, were 244M. Eek.

PID USER            PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
53749 some_user     15   0  337m 244m 2912 S    0  2.0   0:17.49 mongrel_rails

Running Bleakhouse on our rails app, i was amazed at the number of objects created. over 2M!

$ BLEAK_HOUSE=1 ruby-bleak-house ./script/runner 'puts 1'
** Bleakhouse: installed
1
** BleakHouse: working...
** BleakHouse: complete
** Bleakhouse: Run 'bleak /tmp/bleak.53749.0.dump' to analyze.

$ bleak /tmp/bleak.53749.0.dump
Displaying top 20 most common line/class pairs
2,047,025 total objects
2,047,025 filled heap slots
2,403,764 free heap slots
1779063 __null__:__null__:__node__
197423 __null__:__null__:String
16519 __null__:__null__:Array
12728 __null__:__null__:ActionController::Routing::DividerSegment
10495 __null__:__null__:Hash
5676 __null__:__null__:ActionController::Routing::StaticSegment
5436 __null__:__null__:Class
5132 __null__:__null__:Regexp
4525 __null__:__null__:ActionController::Routing::DynamicSegment
2524 __null__:__null__:ActionController::Routing::Route
1307 __null__:__null__:Gem::Version

Whats up with all those routing objects! So i tried a blank routes.rb file….

519,307 total objects
519,307 filled heap slots
233,503 free heap slots

Arghh…. 1.5M objects just because of routes.rb. I know our application is large, lots of resources and nested resources, but thats crazy.

$ rake routes | wc -l
2516

Ok, so taking a closer look, I realized something. Each resource route has a corresponding formatted_* route, lots of which we dont use. So now for some nasty monkey-patching.

ActionController::Routing::RouteSet::Mapper.class_eval do
protected

  def map_unnamed_routes(map, path_without_format, options)
    map.connect(path_without_format, options)
    #map.connect("#{path_without_format}.:format", options)
  end

  def map_named_routes(map, name, path_without_format, options)
    map.named_route(name, path_without_format, options)
    #map.named_route("formatted_#{name}", "#{path_without_format}.:format", options)
  end
end

I then manually added back the formatted routes we needed, careful to use named routes as “map.formatted_foo_bar”

$ rake routes | wc -l
1490

$ bleak /tmp/bleak.56554.0.dump
1,242,796 total objects
1,242,796 filled heap slots
1,224,309 free heap slots

Awesome. I no longer create almost 800k objects.

PID USER            PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
56554 someuser     15   0  249m 156m 2912 S    0  1.3   0:09.92 mongrel_rails

244m –> 156m

This is not a very elegant solution… but I saved almost 100m per mongrel. Ohh.. and it reduced startup time by 50%.

How big are your mongrels?

How does Merb’s router differ from Rails routing? Worth investigating?