ruby-on-rails – 我是否正确地在Heroku Unicorn中预加载应用程

我在http://codelevy.com/2010/02/09/getting-started-with-unicorn.html和https://github.com/blog/517-unicorn做了一些阅读

这两篇文章建议使用preload_app true.还有一个after_fork和before_fork块.

在Rails 3中,还是需要before_block中的代码吗？我在某处读,否则.任何经历过这种情况并且想要分享的人？

我错过了什么吗？我是否正确加载了应用程序？

# config/initializers/unicorn.rb
# Read from:
# http://michaelvanrooijen.com/articles/2011/06/01-more-concurrency-on-a-single-heroku-dyno-with-the-new-celadon-cedar-stack/
worker_processes 3 # amount of unicorn workers to spin up
timeout 30         # restarts workers that hang for 90 seconds

# Noted from http://codelevy.com/2010/02/09/getting-started-with-unicorn.html
# and https://github.com/blog/517-unicorn
preload_app true

after_fork do |server,worker|
  ActiveRecord::Base.establish_connection
end

before_fork do |server,worker|
  ##
  # When sent a USR2,Unicorn will suffix its pidfile with .oldbin and
  # immediately start loading up a new version of itself (loaded with a new
  # version of our app). When this new Unicorn is completely loaded
  # it will begin spawning workers. The first worker spawned will check to
  # see if an .oldbin pidfile exists. If so,this means we've just booted up
  # a new Unicorn and need to tell the old one that it can now die. To do so
  # we send it a QUIT.
  #
  # Using this method we get 0 downtime deploys.

  old_pid = Rails.root + '/tmp/pids/unicorn.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
      # someone else did our job for us
    end
  end
end