Rails 3 + Daemons gem：查询 model 时出现异常

Question

作为我的 Rails 项目的一部分，我们将使用守护进程作为消息队列侦听器来执行来自 Rails RESTful Web 服务前端的命令。

为了便于原型设计，我们使用 Daemons gem 来创建一个非常简单的守护进程。 现在，它超级简单。 这是代码：

require 'rubygems'
require 'daemons'

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

Daemons.run_proc('aeon_server') do
    loop do
        empires = Empire.all
        sleep(5)
    end
end

基本上，它需要守护进程的东西，然后需要我的 Ruby 环境，然后启动到守护进程。 守护进程只是尝试从 Empires 表中查询所有内容。 然后它睡觉并再次这样做。

当它执行“全部”时，出现以下异常：

C:/Ruby/lib/ruby/gems/1.9.1/gems/activesupport-3.0.7/lib/active_support/buffered_logger.rb:109:in `write': closed stream (IOError)
from C:/Ruby/lib/ruby/gems/1.9.1/gems/activesupport-3.0.7/lib/active_support/buffered_logger.rb:109:in `block in flush'
from <internal:prelude>:10:in `synchronize'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/activesupport-3.0.7/lib/active_support/buffered_logger.rb:102:in `flush'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/activesupport-3.0.7/lib/active_support/buffered_logger.rb:126:in `auto_flush'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/activesupport-3.0.7/lib/active_support/buffered_logger.rb:67:in `add'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/activesupport-3.0.7/lib/active_support/buffered_logger.rb:78:in `debug'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/activerecord-3.0.7/lib/active_record/connection_adapters/abstract_adapter.rb:206:in `rescue in log'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/activerecord-3.0.7/lib/active_record/connection_adapters/abstract_adapter.rb:199:in `log'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/activerecord-3.0.7/lib/active_record/connection_adapters/sqlite_adapter.rb:135:in `execute'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/activerecord-3.0.7/lib/active_record/connection_adapters/sqlite_adapter.rb:284:in `select'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/activerecord-3.0.7/lib/active_record/connection_adapters/abstract/database_statements.rb:7:in `select_all'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/activerecord-3.0.7/lib/active_record/connection_adapters/abstract/query_cache.rb:56:in `select_all'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/activerecord-3.0.7/lib/active_record/base.rb:468:in `find_by_sql'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/activerecord-3.0.7/lib/active_record/relation.rb:64:in `to_a'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/activerecord-3.0.7/lib/active_record/relation/finder_methods.rb:143:in `all'
from C:in `all'
from script/aeon_server_control.rb:9:in `block (2 levels) in <main>'
from script/aeon_server_control.rb:7:in `loop'
from script/aeon_server_control.rb:7:in `block in <main>'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/daemons-1.1.3/lib/daemons/application.rb:249:in `call'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/daemons-1.1.3/lib/daemons/application.rb:249:in `block in start_proc'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/daemons-1.1.3/lib/daemons/application.rb:260:in `call'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/daemons-1.1.3/lib/daemons/application.rb:260:in `start_proc'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/daemons-1.1.3/lib/daemons/application.rb:293:in `start'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/daemons-1.1.3/lib/daemons/controller.rb:73:in `run'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/daemons-1.1.3/lib/daemons.rb:195:in `block in run_proc'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/daemons-1.1.3/lib/daemons/cmdline.rb:109:in `call'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/daemons-1.1.3/lib/daemons/cmdline.rb:109:in `catch_exceptions'
from C:/Ruby/lib/ruby/gems/1.9.1/gems/daemons-1.1.3/lib/daemons.rb:194:in `run_proc'
from script/aeon_server_control.rb:6:in `<main>'

知道 ActiveSupport 为何抛出此异常吗？ 除了需要环境之外，我还需要其他步骤将我的 rails 环境“引导”到守护程序吗？

Answer 1

当进程被分叉/生成/不管它在 Windows 上被称为什么时，文件描述符有一些复杂性。

在使用 Rails.logger = ActiveSupport::BufferedLogger.new('/path/to/log') 执行 Daemons.run_proc('aeon_server') 后尝试重新实例化记录器