Thin fails spawning workers when running on EventMachine - ruby

Question

I have a ruby web- / data-server application which is built on a Sinatra foundation. I'm adding EventMachine and em-websocket so that I can have async data transfer connections.
#! /usr/bin/env ruby
require 'yajl'
require 'json'
require 'em-websocket'
require 'sinatra/base'
require 'thin'
require './Actors/DataProvider.rb'
my_host = '10.2.56.87'
my_web_port = '4004'
my_web_sock = '8008'
EventMachine.epoll # choose kernel epoll over select for deterministic execution under load
EventMachine.run do
class SinatraApp < Sinatra::Base
configure do
set :bind, '10.2.56.87'
set :port, '4004'
end
encoder = Yajl::Encoder.new
communicator = DataProvider.new( encoder )
get '/' do
redirect '/index-work.html'
end
before do
content_type 'application/json'
end
post '/auth' do
end
post '/data/:id' do
puts 'got d i '
end
end
EventMachine::WebSocket.start( :host => my_host, :port => my_web_sock ) do | ws |
ws.onopen do
end
ws.onmessage do
end
ws.onclose do
end
end
begin
SinatraApp.run!
rescue => ex
puts "#{ ex.class}: #{ ex.message }"
end
end
The Thin server worked fine when just serving Sinatra, but now that I've added the EM foundation the following occurs:
/usr/local/rvm/gems/ruby-1.9.3-p286/gems/thin-2.0.0.pre/lib/thin/server.rb:192:in `block (2 levels) in start': undefined method `attach_server' for EventMachine:Module (NoMethodError)
from /usr/local/rvm/gems/ruby-1.9.3-p286/gems/thin-2.0.0.pre/lib/thin/server.rb:191:in `each'
from /usr/local/rvm/gems/ruby-1.9.3-p286/gems/thin-2.0.0.pre/lib/thin/server.rb:191:in `block in start'
from /usr/local/rvm/gems/ruby-1.9.3-p286/gems/thin-2.0.0.pre/lib/thin/backends/prefork.rb:30:in `block (2 levels) in start'
from /usr/local/rvm/gems/ruby-1.9.3-p286/gems/eventmachine-1.0.0/lib/eventmachine.rb:187:in `call'
from /usr/local/rvm/gems/ruby-1.9.3-p286/gems/eventmachine-1.0.0/lib/eventmachine.rb:187:in `run_machine'
from /usr/local/rvm/gems/ruby-1.9.3-p286/gems/eventmachine-1.0.0/lib/eventmachine.rb:187:in `run'
from /usr/local/rvm/gems/ruby-1.9.3-p286/gems/thin-2.0.0.pre/lib/thin/backends/prefork.rb:23:in `block in start'
from /usr/local/rvm/gems/ruby-1.9.3-p286/gems/preforker-0.1.1/lib/preforker/worker.rb:52:in `call'
from /usr/local/rvm/gems/ruby-1.9.3-p286/gems/preforker-0.1.1/lib/preforker/worker.rb:52:in `work'
from /usr/local/rvm/gems/ruby-1.9.3-p286/gems/preforker-0.1.1/lib/preforker.rb:129:in `block (2 levels) in spawn_missing_workers'
from (eval):6:in `block in fork'
from (eval):6:in `fork'
from (eval):6:in `fork'
from /usr/local/rvm/gems/ruby-1.9.3-p286/gems/preforker-0.1.1/lib/preforker.rb:126:in `block in spawn_missing_workers'
from /usr/local/rvm/gems/ruby-1.9.3-p286/gems/preforker-0.1.1/lib/preforker.rb:124:in `times'
from /usr/local/rvm/gems/ruby-1.9.3-p286/gems/preforker-0.1.1/lib/preforker.rb:124:in `spawn_missing_workers'
from /usr/local/rvm/gems/ruby-1.9.3-p286/gems/preforker-0.1.1/lib/preforker.rb:44:in `run'
from /usr/local/rvm/gems/ruby-1.9.3-p286/gems/thin-2.0.0.pre/lib/thin/backends/prefork.rb:37:in `start'
from /usr/local/rvm/gems/ruby-1.9.3-p286/gems/thin-2.0.0.pre/lib/thin/server.rb:187:in `start'
from /usr/local/rvm/gems/ruby-1.9.3-p286/gems/rack-1.4.1/lib/rack/handler/thin.rb:13:in `run'
from /usr/local/rvm/gems/ruby-1.9.3-p286/gems/sinatra-1.3.3/lib/sinatra/base.rb:1350:in `run!'
from /home/devel/ISF_Server/server-work.rb:122:in `block in <top (required)>'
from /usr/local/rvm/gems/ruby-1.9.3-p286/gems/eventmachine-1.0.0/lib/eventmachine.rb:187:in `call'
from /usr/local/rvm/gems/ruby-1.9.3-p286/gems/eventmachine-1.0.0/lib/eventmachine.rb:187:in `run_machine'
from /usr/local/rvm/gems/ruby-1.9.3-p286/gems/eventmachine-1.0.0/lib/eventmachine.rb:187:in `run'
from /home/devel/ISF_Server/server-work.rb:15:in `<top (required)>'
from /usr/local/rvm/gems/ruby-1.9.3-p286/gems/ruby-debug-ide-0.4.17.beta14/lib/ruby-debug-ide.rb:127:in `debug_load'
from /usr/local/rvm/gems/ruby-1.9.3-p286/gems/ruby-debug-ide-0.4.17.beta14/lib/ruby-debug-ide.rb:127:in `debug_program'
from /usr/local/rvm/gems/ruby-1.9.3-p286/gems/ruby-debug-ide-0.4.17.beta14/bin/rdebug-ide:118:in `<top (required)>'
from -e:1:in `load'
from -e:1:in `<main>'
I do notice that the Thin gem was recently updated, but EM has not been. That's my next point of inquiry. Somebody else posted that Thin should not be run from within EM.run block, but the example I am building from had it this way.

Answer 1

Okay. I corresponded with Marc-Andre Cournoyer directly. He says, first, don't spawn This (through Sinatra) inside an EM.run block.
Secondly, the error is generated from Thin 2 (pre) which requires the EventMachine live Edition, or gem eventmachine-le.
Mo' bettah now. :D