在 unicorn 上跑是正常的。rainbows 延用 unicorn 的配置，加上

worker_processes 4 
 Rainbows! do
   use :FiberSpawn
   worker_connections 20
 end

rainbows.rb 的完整配置如下：

# -*- encoding: utf-8 -*-
module Rails
  class <<self
    def root
      File.expand_path(__FILE__).split('/')[0..-3].join('/')
    end
  end
end

rails_env = ENV["RAILS_ENV"] || "production"

   worker_processes 4 # assuming four CPU cores
    Rainbows! do
      use :FiberSpawn
      worker_connections 8
    end

preload_app true
working_directory Rails.root
pid "/tmp/rainbows.pid"
stderr_path "/tmp/log/rainbows.log"
stdout_path "/tmp/log/rainbows.log"

listen 3001, :tcp_nopush => false

listen "/tmp/rainbows.xrk_crm.sock", backlog: 1024
#worker_processes 8
timeout 30

if GC.respond_to?(:copy_on_write_friendly=)
  GC.copy_on_write_friendly = true
end

before_exec do |server|
  ENV["BUNDLE_GEMFILE"] = "#{Rails.root}/Gemfile"
end

before_fork do |server, worker|
  old_pid = "#{Rails.root}/tmp/pids/rainbows.pid.oldbin"
  if File.exists?(old_pid) && server.pid != old_pid
    begin
      Process.kill("QUIT", File.read(old_pid).to_i)
    rescue Errno::ENOENT, Errno::ESRCH
      puts "Send 'QUIT' signal to rainbows error!"
    end
  end
end

启动命令： bundle exec rainbows -c config/rainbows.rb -E staging -D

进程是启动了。但访问的时候出现“ActionView::Template::Error (stack level too deep): /usr/local/rvm/rubies/ruby-1.9.3-p392/lib/ruby/1.9.1/psych/visitors/to_ruby.rb:104”

这是怎么回事呢