Mysql Rails 3.1+；守护进程宝石赢了'；I don’我不能访问我的数据库

我正在尝试为运行在Ubuntu服务器上的Rails 3.1应用程序设置一个守护进程。就这么简单：

require File.expand_path('../../config/environment',  __FILE__)
require 'rubygems'
require 'daemons'

Daemons.run_proc('my_script') do
  loop do
    puts BlogPost.count
    sleep(5)
  end
end

require 'rubygems'
require 'daemons'

Daemons.run_proc('my_script') do 
  require File.expand_path('../../config/environment',  __FILE__)
  ActiveRecord::Base.logger = ActiveSupport::BufferedLogger.new('/path/to/log/file.log')
  loop do
    puts BlogPost.count
    sleep(5)
  end
end

但是当我进入

BlogPost.count

时，我得到以下错误：

/usr/lib/ruby/gems/1.8/gems/activerecord-3.1.0/lib/active_record/connection_adapters/mysql2_adapter.rb:283:in `query': Mysql2::Error: MySQL server has gone away: SHOW FIELDS FROM `blog_posts` (ActiveRecord::StatementInvalid)
from /usr/lib/ruby/gems/1.8/gems/activerecord-3.1.0/lib/active_record/connection_adapters/mysql2_adapter.rb:283:in `execute'
from /usr/lib/ruby/gems/1.8/gems/activerecord-3.1.0/lib/active_record/connection_adapters/abstract_adapter.rb:244:in `log'
from /usr/lib/ruby/gems/1.8/gems/activesupport-3.1.0/lib/active_support/notifications/instrumenter.rb:21:in `instrument'
from /usr/lib/ruby/gems/1.8/gems/activerecord-3.1.0/lib/active_record/connection_adapters/abstract_adapter.rb:239:in `log'
from /usr/lib/ruby/gems/1.8/gems/activerecord-3.1.0/lib/active_record/connection_adapters/mysql2_adapter.rb:283:in `execute'
from /usr/lib/ruby/gems/1.8/gems/activerecord-3.1.0/lib/active_record/connection_adapters/mysql2_adapter.rb:473:in `columns'
from /usr/lib/ruby/gems/1.8/gems/activerecord-3.1.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:95:in `initialize'
from /usr/lib/ruby/gems/1.8/gems/activerecord-3.1.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:185:in `with_connection'
from /usr/lib/ruby/gems/1.8/gems/activerecord-3.1.0/lib/active_record/connection_adapters/abstract/connection_pool.rb:92:in `initialize'
from /usr/lib/ruby/gems/1.8/gems/activerecord-3.1.0/lib/active_record/base.rb:706:in `call'
from /usr/lib/ruby/gems/1.8/gems/activerecord-3.1.0/lib/active_record/base.rb:706:in `default'
from /usr/lib/ruby/gems/1.8/gems/activerecord-3.1.0/lib/active_record/base.rb:706:in `[]'
from /usr/lib/ruby/gems/1.8/gems/activerecord-3.1.0/lib/active_record/base.rb:706:in `columns'
from /usr/lib/ruby/gems/1.8/gems/activerecord-3.1.0/lib/active_record/base.rb:722:in `column_names'
from /usr/lib/ruby/gems/1.8/gems/activerecord-3.1.0/lib/active_record/relation/calculations.rb:192:in `aggregate_column'
from /usr/lib/ruby/gems/1.8/gems/activerecord-3.1.0/lib/active_record/relation/calculations.rb:213:in `execute_simple_calculation'
from /usr/lib/ruby/gems/1.8/gems/activerecord-3.1.0/lib/active_record/relation/calculations.rb:187:in `perform_calculation'
from /usr/lib/ruby/gems/1.8/gems/activerecord-3.1.0/lib/active_record/relation/calculations.rb:155:in `calculate'
from /usr/lib/ruby/gems/1.8/gems/activerecord-3.1.0/lib/active_record/relation/calculations.rb:58:in `count'
from /usr/lib/ruby/gems/1.8/gems/activerecord-3.1.0/lib/active_record/base.rb:445:in `__send__'
from /usr/lib/ruby/gems/1.8/gems/activerecord-3.1.0/lib/active_record/base.rb:445:in `count'
from script/background_job_processor_control.rb:22

知道为什么我的脚本无法连接到MySQL吗？如果我把

BlogPost.count

代码放在

Daemons.run\u proc

之前，我就可以很好地连接到MySQL

----------编辑：解决了------------

对于任何对解决方案好奇的人来说，我必须做三件事才能让它起作用：

启动/停止我的守护程序时包括

bundle exec

：

RAILS\u ENV=production bundle exec myscript.rb start

此时，我停止获取MySQL2错误，但开始获取记录器错误。解决方案是在

run\u proc

块中添加以下代码：

ActiveRecord:：Base.logger=ActiveSupport:：BufferedLogger.new（'/path/to/log/file.log'）

然后我遇到了第三个错误，解决方案是在

run\u proc

块中使用Rails环境，而不是在脚本的前面

我的最终脚本如下所示：

require File.expand_path('../../config/environment',  __FILE__)
require 'rubygems'
require 'daemons'

Daemons.run_proc('my_script') do
  loop do
    puts BlogPost.count
    sleep(5)
  end
end

require 'rubygems'
require 'daemons'

Daemons.run_proc('my_script') do 
  require File.expand_path('../../config/environment',  __FILE__)
  ActiveRecord::Base.logger = ActiveSupport::BufferedLogger.new('/path/to/log/file.log')
  loop do
    puts BlogPost.count
    sleep(5)
  end
end

---

要为脚本正确预加载Rails环境（依赖项），请按如下方式启动它：

bundle exec my_script_ctl start

---

我不知道为什么，但当我在后台监控脚本之前断开数据库连接时，它会起作用，例如：

# app env
ENV['RAILS_ENV'] = 'production'
require File.expand_path(File.dirname(__FILE__) + "/../config/environment")

# disconnect first
ActiveRecord::Base.connection.disconnect!

# Become a daemon
Daemons.daemonize

# connect again
ActiveRecord::Base.establish_connection ENV['RAILS_ENV']

# ... do what you need

---

希望这能有所帮助。

你是用

bundle exec my_script\u ctl start启动守护程序的吗？嗯，不是我在做
RAILS\u ENV=production ruby script/myscript\u control.rb start
。我只是试着按照你的方式来做，现在我得到了一个不同的错误：/usr/lib/ruby/gems/1.8/gems/activesupport-3.1.0/lib/active\u support/buffered\u logger.rb:109:in‘write’：closed stream（IOError），所以我按照这里的建议（）来消除日志错误，我得到了一个新的错误，说我的开发数据库中不存在一些表。但我正试图在生产环境中运行此功能，因此我在
bundle exec
前面添加了
RAILS\u ENV=production
，现在我们回到了“MySQL服务器已消失”的原始错误：（那么故事的另一部分是什么呢？将环境加载到块中而不是文件的顶部。我只是用完整的解决方案编辑了我的问题。