Question

我有使用rails的性能问题。当我对这样的控制器进行ajax调用时：

def test
    @hotels = Hotel.all
    render :json => ['hotels' => @hotels ], :include=> [:country, :city]
end

完成时间可能需要2-5秒。我的数据库中只有40家酒店。我认为它很长......例如，Django上的相同请求将花费400毫秒

我忘了配置好我的环境吗？

我使用Rails entreprise版本和乘客。

编辑：我的日志文件：

     Started GET "/hotels/test.json" for 172.16.81.1 at Wed Oct 12 22:11:06 +0200 2011
    [paperclip] Duplicate URL for image with /system/:attachment/:id/:style/:filename. This will clash with attachment defined in HotelImage class
    [paperclip] Duplicate URL for thumbnail with /system/:attachment/:id/:style/:filename. This will clash with attachment defined in Hotel class
    [paperclip] Duplicate URL for map with /system/:attachment/:id/:style/:filename. This will clash with attachment defined in Hotel class
    [paperclip] Duplicate URL for thumbnail with /system/:attachment/:id/:style/:filename. This will clash with attachment defined in DestinationAlbumPhoto class
    [paperclip] Duplicate URL for map with /system/:attachment/:id/:style/:filename. This will clash with attachment defined in Destination class
    [paperclip] Duplicate URL for image with /system/:attachment/:id/:style/:filename. This will clash with attachment defined in Continent class
    [paperclip] Duplicate URL for thumbnail with /system/:attachment/:id/:style/:filename. This will clash with attachment defined in Destination class
    [paperclip] Duplicate URL for image with /system/:attachment/:id/:style/:filename. This will clash with attachment defined in Event class
    [paperclip] Duplicate URL for thumbnail with /system/:attachment/:id/:style/:filename. This will clash with attachment defined in HotelAlbumPhoto class
    [paperclip] Duplicate URL for map with /system/:attachment/:id/:style/:filename. This will clash with attachment defined in Event class
      Processing by HotelController#test as JSON
      [1m[36mHotel Load (0.2ms)[0m  [1mSELECT `hotels`.* FROM `hotels`[0m
      [1m[35mCountry Load (0.1ms)[0m  SELECT `countries`.* FROM `countries` WHERE (`countries`.`id` = 3)
      [1m[36mCity Load (0.1ms)[0m  [1mSELECT `cities`.* FROM `cities` WHERE (`cities`.`id` = 2)[0m
    Completed 200 OK in 405ms (Views: 366.1ms | ActiveRecord: 0.3ms)

写的是405ms，但firefox告诉我3,7秒。

我的酒店模特：

class Hotel < ActiveRecord::Base
  cattr_reader :per_page
  @@per_page = 16

  belongs_to :hotel_type
  belongs_to :hotel_theme
  belongs_to :country
  belongs_to :city
  belongs_to :destination
  belongs_to :continent

  has_many :hotel_comments, :dependent => :destroy

  has_many :hotel_album_photos, :dependent => :destroy

  has_many :hotel_activity_values

  has_many :hotel_service_values

  accepts_nested_attributes_for :hotel_album_photos

  has_attached_file :thumbnail, :styles => { :medium => "300x300>", :thumb => "191x134>"} , :default_url => '/images/default/missing.png' 
  has_attached_file :map, :styles => { :medium => "300x300>", :thumb => "191x134>"} , :default_url => '/images/default/missing.png' 

  scope :country, lambda { |country_id|
     self.scoped.where('country_id IN ( ? )', country_id) unless country_id.blank?
  }

  scope :selection, lambda { |selection|
     self.scoped.where('selection = ? ', 1) unless selection.blank?
  }

  scope :city, lambda { |city_id|
      self.scoped.where('city_id IN ( ? )', city_id) unless city_id.blank?
  }

  scope :hoteltype, lambda { |type|
      self.scoped.where('hotel_type_id IN ( ? )', type) unless type.blank?
   }

  scope :theme, lambda { |theme|
      self.scoped.where('hotel_theme_id IN ( ? )', theme) unless theme.blank?
   }

  scope :prices, lambda { |prices|
      condition = []
      prices.each do |price|
        pricesArray = price.split('-')
        condition.push '(price BETWEEN ' + pricesArray[0] + ' AND ' + pricesArray[1] + ')'
      end
      self.scoped.where(condition.join(' OR ')) 
   }

   scope :order_by_price, lambda { |direction|
     self.scoped.order('price ' + direction)
   }

   scope :order_by_rate, lambda { |rate|
     self.scoped.order('global_rate ' + rate)
   }

   scope :services, lambda { |services|
      {:joins => [:hotel_service_values ]  , :conditions => { :hotel_service_values => {:hotel_service_id  => services}}}
   }

  scope :limiter, lambda { |limiter|
      self.scoped.limit(limiter)
   }

end

感谢您的帮助。

Answer 1

看着你的代码，我的猜测是你有一个简单的“N + 1”问题。

即您将@hotels加载到数组中，但是当您生成json时您加载country和城市for each酒店。

因此，对于您的40家酒店，您必须总共进行81次数据库查询。

这可以通过在加载时执行include来简单地改进。

旧样式

Hotel.all(:include => [:country, :city])

以Rails 3风格

Hotel.includes(:country, :city).all

通过此更改，您应该只进行3次数据库调用。

有关详细信息，请参阅Eager Loading上的Rails指南。

Answer 2

看着Log，Rails似乎认为它在405毫秒内得到了响应。这使得堆栈的其余部分需要考虑：

Rails（✓）
乘客
的Apache
网络
DNS解析
浏览器呈现

首先，看看其他浏览器的情况。我在使用Firefox的一个（非rails）网站上看到了偶尔的问题，而基于Webkit的浏览器（Safari，Chrome）也没问题。也许Firefox因某种原因而窒息（例如DNS resolving issues或其他原因）。

如果所有浏览器都相同（或者特别是，如果Firefox是罪魁祸首），那么打开Firebug并查看Net选项卡，尤其是其下的XHR（AJAX）选项卡。将鼠标悬停在其中一个查询的时间栏上，查看时间的细分：DNS，连接，发送，等待，接收。

如果Firebug指示请求本身花费的时间（发送，等待，接收），那么请查看Apache日志 - 打开CustomLog时间报告（添加%D - {{ 3}}）看看Apache认为这些请求需要多长时间。

这应该缩小您的问题以进一步分析原因。

Answer 3

我正在使用VMWare来运行我的Web服务器。我的表演问题就是这个问题。我在这里找到了解决方案：

Webrick is very slow to respond. How to speed it up?

铁轨上的表现

3 个答案: