fcgi.rbのpure-rubyモード

fcgi.rbを見ていると、冒頭が

begin
  raise LoadError if defined?(FCGI_PURE_RUBY) && FCGI_PURE_RUBY
  require "fcgi.so"
rescue LoadError
  require 'socket'
  require 'stringio'

  class FCGI

と書かれているので、ひょっとしたらFCGI_PURE_RUBYを真にしたら、pure-rubyモードでFastCGIが動くんでないの? と思って早速やってみたのだが、

FCGI_PURE_RUBY = true

begin
  raise LoadError if defined?(FCGI_PURE_RUBY) && FCGI_PURE_RUBY
  require "fcgi.so"
rescue LoadError
  require 'socket'
  require 'stringio'

  class FCGI
[04/Feb/2009:10:44:31 :: 1052] Dispatcher failed to catch: Bad file descriptor (Errno::EBADF)
  E:/ruby/lib/ruby/gems/1.8/gems/actionpack-2.2.2/lib/action_controller/dispatcher.rb:66:in `write'
  E:/ruby/lib/ruby/gems/1.8/gems/actionpack-2.2.2/lib/action_controller/dispatcher.rb:66:in `puts'
  E:/ruby/lib/ruby/gems/1.8/gems/actionpack-2.2.2/lib/action_controller/dispatcher.rb:66:in `failsafe_response'
  E:/ruby/lib/ruby/gems/1.8/gems/actionpack-2.2.2/lib/action_controller/dispatcher.rb:187:in `failsafe_rescue'
  E:/ruby/lib/ruby/gems/1.8/gems/actionpack-2.2.2/lib/action_controller/dispatcher.rb:135:in `dispatch_cgi'
  E:/ruby/lib/ruby/gems/1.8/gems/actionpack-2.2.2/lib/action_controller/dispatcher.rb:39:in `dispatch'
  E:/ruby/lib/ruby/gems/1.8/gems/rails-2.2.2/lib/fcgi_handler.rb:101:in `process_request'
  E:/ruby/lib/ruby/gems/1.8/gems/rails-2.2.2/lib/fcgi_handler.rb:151:in `with_signal_handler'
  E:/ruby/lib/ruby/gems/1.8/gems/rails-2.2.2/lib/fcgi_handler.rb:99:in `process_request'
  E:/ruby/lib/ruby/gems/1.8/gems/rails-2.2.2/lib/fcgi_handler.rb:76:in `process_each_request'
  E:/ruby/lib/ruby/site_ruby/1.8/fcgi.rb:594:in `each_cgi'
  E:/ruby/lib/ruby/gems/1.8/gems/rails-2.2.2/lib/fcgi_handler.rb:75:in `process_each_request'
  E:/ruby/lib/ruby/gems/1.8/gems/rails-2.2.2/lib/fcgi_handler.rb:74:in `catch'
  E:/ruby/lib/ruby/gems/1.8/gems/rails-2.2.2/lib/fcgi_handler.rb:74:in `process_each_request'
  E:/ruby/lib/ruby/gems/1.8/gems/rails-2.2.2/lib/fcgi_handler.rb:49:in `process!'
  E:/ruby/lib/ruby/gems/1.8/gems/rails-2.2.2/lib/fcgi_handler.rb:23:in `process!'
  E:/www/addressbook/public/dispatch.fcgi:24
unhandled dispatch error

これ以上はFastCGIのプロトコルを知らないとデバッグできないし、駄目か... orz
やはりpure-rubyで動かすことなんて考慮されている訳ないよな。