MongoMapper、MongoDB 和 EventMachine

Question

我正在使用 DaemonKit 创建 AMQP 侦听器。每当一条消息通过网络时，我都会将其记录到 MongoDB 中。我已将 Rails MongoDB 配置移过来，并且连接工作正常。当我尝试创建新模型时，Model.create 方法中出现错误。

IOError when attempting to close socket connected to localhost:27017: #<IOError: closed stream>
/Users/lfaus/.rvm/gems/ruby-1.9.2-p180/gems/mongo-1.3.1/lib/mongo/connection.rb:856:in `rescue in send_message_on_socket': Operation failed with the following exception: closed stream (Mongo::ConnectionFailure)
from /Users/lfaus/.rvm/gems/ruby-1.9.2-p180/gems/mongo-1.3.1/lib/mongo/connection.rb:843:in `send_message_on_socket'
from /Users/lfaus/.rvm/gems/ruby-1.9.2-p180/gems/mongo-1.3.1/lib/mongo/connection.rb:483:in `block in receive_message'
from <internal:prelude>:10:in `synchronize'
from /Users/lfaus/.rvm/gems/ruby-1.9.2-p180/gems/mongo-1.3.1/lib/mongo/connection.rb:482:in `receive_message'
from /Users/lfaus/.rvm/gems/ruby-1.9.2-p180/gems/mongo-1.3.1/lib/mongo/cursor.rb:407:in `block in send_initial_query'
from /Users/lfaus/.rvm/gems/ruby-1.9.2-p180/gems/mongo-1.3.1/lib/mongo/connection.rb:609:in `instrument'
from /Users/lfaus/.rvm/gems/ruby-1.9.2-p180/gems/mongo-1.3.1/lib/mongo/cursor.rb:406:in `send_initial_query'
from /Users/lfaus/.rvm/gems/ruby-1.9.2-p180/gems/mongo-1.3.1/lib/mongo/cursor.rb:371:in `refresh'
from /Users/lfaus/.rvm/gems/ruby-1.9.2-p180/gems/mongo-1.3.1/lib/mongo/cursor.rb:87:in `next_document'
from /Users/lfaus/.rvm/gems/ruby-1.9.2-p180/gems/mongo-1.3.1/lib/mongo/cursor.rb:248:in `each'
from /Users/lfaus/.rvm/gems/ruby-1.9.2-p180/gems/mongo-1.3.1/lib/mongo/cursor.rb:267:in `to_a'
from /Users/lfaus/.rvm/gems/ruby-1.9.2-p180/gems/mongo-1.3.1/lib/mongo/cursor.rb:267:in `to_a'
from /Users/lfaus/.rvm/gems/ruby-1.9.2-p180/gems/plucky-0.3.8/lib/plucky/query.rb:76:in `all'
from /Volumes/External/Projects/ruby/alertsdaemons/eventmachine/libexec/eventmachine-daemon.rb:17:in `block in <top (required)>'
from /Volumes/External/Projects/ruby/alertsdaemons/eventmachine/libexec/eventmachine-daemon.rb:15:in `loop'
from /Volumes/External/Projects/ruby/alertsdaemons/eventmachine/libexec/eventmachine-daemon.rb:15:in `<top (required)>'
from /Users/lfaus/.rvm/gems/ruby-1.9.2-p180/gems/activesupport-3.0.7/lib/active_support/dependencies.rb:239:in `require'
from /Users/lfaus/.rvm/gems/ruby-1.9.2-p180/gems/activesupport-3.0.7/lib/active_support/dependencies.rb:239:in `block in require'
from /Users/lfaus/.rvm/gems/ruby-1.9.2-p180/gems/activesupport-3.0.7/lib/active_support/dependencies.rb:225:in `block in load_dependency'
from /Users/lfaus/.rvm/gems/ruby-1.9.2-p180/gems/activesupport-3.0.7/lib/active_support/dependencies.rb:596:in `new_constants_in'
from /Users/lfaus/.rvm/gems/ruby-1.9.2-p180/gems/activesupport-3.0.7/lib/active_support/dependencies.rb:225:in `load_dependency'
from /Users/lfaus/.rvm/gems/ruby-1.9.2-p180/gems/activesupport-3.0.7/lib/active_support/dependencies.rb:239:in `require'
from /Users/lfaus/.rvm/gems/ruby-1.9.2-p180/gems/daemon-kit-0.1.8.2/lib/daemon_kit/application.rb:38:in `run'
from /Users/lfaus/.rvm/gems/ruby-1.9.2-p180/gems/daemon-kit-0.1.8.2/lib/daemon_kit/application.rb:21:in `exec'
from /Volumes/External/Projects/ruby/alertsdaemons/eventmachine/bin/eventmachine:12:in `<top (required)>'
from -e:1:in `load'
from -e:1:in `<main>'

创建对象的代码：

# Sample loop to show process
loop do
  DaemonKit.logger.info "I'm running"
  message = Message.create({
    :first_name => 'Lee',
    :last_name => 'Faus'
  })
  puts message.inspect
  puts message.count
  sleep 5
end

我读过我可以分叉 mongomapper 以使 http 调用异步，但这些错误似乎来自 mongodb ruby​​ 驱动程序。非常感谢任何帮助。

Answer 1

很难说这里到底发生了什么，但我怀疑我希望你调查一下。

确保您在 POST-daemonize 配置中建立 Mongo 连接，而不是在 PRE-daemonize 配置中。 DaemonKit 在 PRE 初始化程序之后分叉，此时需要重新建立 mongo 连接。这适用于任何类型的 IO，分叉后它们都需要重新打开。

同样的逻辑也适用于守护进程项目中的 ActiveRecord。如果这是 ActiveRecord 你可以这样做：

config/pre-daemonize/database.rb

    ActiveRecord::Base.establish_connection(:foo => 'bar')

config/post-daemonize/database.rb

    ActiveRecord::Base.verify_active_connections!

我不是 mongomapper 用户，所以我不知道如何翻译上面的例子。

我最好的建议是在守护进程前阶段“ping”mongo，如果失败则出错，这样守护进程甚至不会启动，并在守护进程后配置中正确设置连接。