ruby-on-rails-3.2 - 如何优雅地重启 unicorn ？

Question

我有一台服务器，每 1 分钟与厨师一起部署。为了重启 unicorn ，我将 USR2 信号发送给老主人，然后尝试通过代码减少老 worker :

before_fork do |server, worker|

  # the following is highly recomended for Rails + "preload_app true"
  # as there's no need for the master process to hold a connection
  defined?(ActiveRecord::Base) and
    ActiveRecord::Base.connection.disconnect!

  # This allows a new master process to incrementally
  # phase out the old master process with SIGTTOU to avoid a
  # thundering herd when doing a transparent upgrade. The last worker
  # spawned will then kill off the old master process with a SIGQUIT.
  old_pid = "#{server.config[:pid]}.oldbin"
  if old_pid != server.pid
    begin
      sig = (worker.nr + 1) >= server.worker_processes ? :QUIT : :TTOU
      Process.kill(sig, File.read(old_pid).to_i)
    rescue Errno::ENOENT, Errno::ESRCH
    end
  end

  # sleep 1
end

最后，向老主人发送 QUIT 信号

每次我在日志中收到以下消息:

E, [2013-07-03T10:56:19.983813 #19955] ERROR -- : retrying in 0.5 seconds (1 tries left)
E, [2013-07-03T10:56:20.484468 #19955] ERROR -- : adding listener failed addr=0.0.0.0:3000 (in use)
E, [2013-07-03T10:56:20.484595 #19955] ERROR -- : retrying in 0.5 seconds (0 tries left)
E, [2013-07-03T10:56:20.985190 #19955] ERROR -- : adding listener failed addr=0.0.0.0:3000 (in use)                   
/my_path/766ea02ce174c37de606c1960c498d53c5fb602b/vendor/bundle/ruby/1.9.1/gems/unicorn-4.4.0/lib/unicorn/socket_helper.rb:147:in `initialize': Address  already in use - bind(2) (Errno::EADDRINUSE) 

这意味着新的master无法启动(我在进程列表中没有看到new master)但是旧的master无法关闭并且worker的数量是恒定的。

我可能做错了什么？谢谢)

Answer 1

重新启动 unicorn 的优雅方式将是 Rakefile 中的 rake 任务:

task :restart_server => :environment do
     system("kill -QUIT `cat pids/unicorn.pid`")
     system("bundle exec unicorn_rails -c ./config/unicorn.rb -D")
end

此处假定文件“unicorn.pid”的路径，主服务器进程存在于application_root/pids/unicorn.pid 中。这个路径可以通过改变config/unicorn.rb中pid的值来改变

pid "pids/unicorn.pid"

此外，如果您使用 cap 进行部署，请确保此文件在远程服务器上具有写入权限，并将此文件添加到 .gitignore，以便此文件不会将您的本地 pid 值覆盖到远程生产和测试服务器上。