Ruby on rails Ruby Mongo或Mongoid并发问题

我认为这一定是并发问题。我使用的是passenger、rails 2.3.5、mongoid 1.9.2和mongo ruby驱动程序1.0.9。我使用jQuery请求从MongoDB中提取的数据，然后在浏览器中呈现。在我开始同时提出两个这样的要求之前，一切都很顺利。在模型中，这些是由请求执行的方法：

Class Visit
  include Mongoid::Document
  ...
  def self.cancellations_and_visits_by_therapist_graph(clinic_id) 
    visits = collection.group("function(x){ return { resource_id : x.resource_id } }",
            {:clinic_id => clinic_id, :visit_date => { "$gte" => Time.now - 6.months, "$lte" => Time.now}}, 
            {:visits => 0, :cancel_no_shows => 0},
            'function(obj, count) {
              if (obj.visit_status == "NO SHOW" || obj.visits_status == "CANCELLED") {
                count.cancel_no_shows += 1;
              } else {
                count.visits += 1;
              }

            }')

    visits = visits.group_by {|g| g['resource_id']}

    Resource.any_in(:mysql_id => visits.keys).order_by([:last_name, :asc]).order_by([:first_name, :asc]).inject({ 'visits' => [], 'cancel_no_shows' => [], 'xlabels' => []}) do |formatted_visits, resource|
      formatted_visits['visits'] << visits[resource.mysql_id.to_f].first['visits']
      formatted_visits['cancel_no_shows'] << visits[resource.mysql_id.to_f].first['cancel_no_shows']
      formatted_visits['xlabels'] << resource.last_name + ", " + resource.first_name
      formatted_visits
    end
  end



  def self.total_visits_for_graph(practice_id)
    visits = collection.group("function(x) { return { clinic_id : x.clinic_id } }", 
                          {:practice_id => practice_id, :visit_status => 'COMPLETE', :visit_date => { "$gte" => Time.now - 6.months, "$lte" => Time.now}},
                          {:visits => 0}, "function(obj, count) { count.visits += 1; }")

    visits = visits.group_by {|g| g['clinic_id']}
    Clinic.any_in(:mysql_id => visits.keys).order_by([:name, :asc]).inject({ 'data' => [], 'xlabels' => []}) do |formatted_visits, clinic|
      formatted_visits['data'] << visits[clinic.mysql_id.to_f].first['visits']
      formatted_visits['xlabels'] << clinic.name
      formatted_visits
    end
  end
end

此（诊所对象）由collection.group调用返回：

{"_id"=>BSON::ObjectId('4cb7d72b3bc5457800ce2e6f'), "name"=>"Corona", "practice_id"=>39, "mysql_id"=>101}

与所有好的一致性问题一样，结果是随机的，有时效果很好，有时会崩溃。我是mongo和mongoid的新手，所以我不确定这是mongoid还是mongoid驱动程序的问题，但是我认为这与mongoid有关。我包括我用来在rails中加载Mongoid的初始值设定项。任何想法，甚至只是额外的调试想法都将不胜感激

联系

mongoid_conf = YAML::load_file(Rails.root.join('config/mongoid.yml'))[Rails.env]

Mongoid.configure do |config|
  config.master = Mongo::Connection.new(mongoid_conf['host'], 27017, :pool_size => 5, :timeout => 5).db(mongoid_conf['database'])
end

---

我找到了这个问题的解决办法。实际上不是Mongo司机或Mongoid，而是乘客。当乘客跨越rails进程时，它会分叉当前实例，以便文件描述符（包括TCP描述符）在应用程序实例之间共享。这意味着mongo正在被同一个套接字写入和读取，这就是导致并发问题的原因。解决方案是让mongo在分叉时重新连接。这就是我找到的解决方案：

# Handle the creation of new processes by Phusion Passenger
if defined?(PhusionPassenger)
  PhusionPassenger.on_event(:starting_worker_process) do |forked|
    if forked
      # We're in smart spawning mode.

      # Reset the connection to MongoDB
      Mongoid.config.master.connection.close
      load File.join(RAILS_ROOT, 'config/initializers/mongoid_init.rb')
    else
      # We're in conservative spawning mode. We don't need to do anything.    
    end
  end
end

原始答案张贴和讨论的参考

# Handle the creation of new processes by Phusion Passenger
if defined?(PhusionPassenger)
  PhusionPassenger.on_event(:starting_worker_process) do |forked|
    if forked
      # We're in smart spawning mode.

      # Reset the connection to MongoDB
      Mongoid.config.master.connection.close
      load File.join(RAILS_ROOT, 'config/initializers/mongoid_init.rb')
    else
      # We're in conservative spawning mode. We don't need to do anything.    
    end
  end
end