Dalli/Memcached 看起来像缓存，但在开发环境中没有缓存答案

【问题标题】：Dalli/Memcached looks like caching but it's not caching in development environmentDalli/Memcached 看起来像缓存，但在开发环境中没有缓存
【发布时间】：2014-04-19 16:09:58
【问题描述】：

Rails 4.0.4
独角兽
达利 2.7
Memcached 1.4.17

development.rb 设置为在开发环境中使用缓存：

  config.cache_classes = true
  config.action_controller.perform_caching = true
  config.cache_store = :dalli_store

奇怪的是在日志中，看看它：

18:57:15 web.1  |   Program Load (3.1ms)  SELECT "programs".* FROM "programs" WHERE "programs"."is_deleted" = 'f' AND (poster_file_name IS NOT NULL) AND ("programs"."poster_file_name" != 'yumurcatvkucuk.jpg') LIMIT 10
18:57:15 web.1  | Cache read: views/programs/21-20140408150833637850000/programs/807-20140408150843947601000/programs/925-20140408150845273240000/programs/872-20140418084359291046000/programs/132-20140408150835259856000/programs/136-20140408150835308846000/programs/140-20140408150835371772000/programs/1280-20140408150849908310000/programs/340-20140408150837584935000/programs/150-20140408150835553155000/adc205508053828cb96d93c37b9ad0f7
18:57:15 web.1  | Read fragment views/programs/21-20140408150833637850000/programs/807-20140408150843947601000/programs/925-20140408150845273240000/programs/872-20140418084359291046000/programs/132-20140408150835259856000/programs/136-20140408150835308846000/programs/140-20140408150835371772000/programs/1280-20140408150849908310000/programs/340-20140408150837584935000/programs/150-20140408150835553155000/adc205508053828cb96d93c37b9ad0f7 (0.6ms)
18:57:15 web.1  |   Rendered pages/index.html.erb within layouts/application (47.8ms)
18:57:15 web.1  |   Program Load (2.8ms)  SELECT "programs".* FROM "programs" WHERE "programs"."is_deleted" = 'f' AND "programs"."category_id" = 10 ORDER BY "programs"."order_no" ASC LIMIT 14
18:57:15 web.1  |   Category Load (2.4ms)  SELECT "categories".* FROM "categories" WHERE "categories"."id" IN (10)
18:57:15 web.1  | Cache read: views/programs/8-20140408150833498130000/programs/19-20140408150833622733000/programs/30-20140408150833742922000/programs/24-20140408150833663802000/programs/1021-20140408150846580202000/programs/872-20140418084359291046000/programs/1187-20140408150848167962000/programs/866-20140408150844626941000/programs/1280-20140408150849908310000/programs/881-20140408150844749467000/programs/1376-20140408150850766221000/programs/1379-20140408150850809312000/programs/1437-20140408150851047434000/programs/3-20140408150832973507000/6c2638ad89493f0c3e448b3d66c4a1de
18:57:15 web.1  | Read fragment views/programs/8-20140408150833498130000/programs/19-20140408150833622733000/programs/30-20140408150833742922000/programs/24-20140408150833663802000/programs/1021-20140408150846580202000/programs/872-20140418084359291046000/programs/1187-20140408150848167962000/programs/866-20140408150844626941000/programs/1280-20140408150849908310000/programs/881-20140408150844749467000/programs/1376-20140408150850766221000/programs/1379-20140408150850809312000/programs/1437-20140408150851047434000/programs/3-20140408150832973507000/6c2638ad89493f0c3e448b3d66c4a1de (0.7ms)
18:57:15 web.1  |   Episode Load (2.8ms)  SELECT "episodes".* FROM "episodes" WHERE "episodes"."is_deleted" = 'f' AND "episodes"."episode_type_id" = 2 ORDER BY "episodes"."id" DESC LIMIT 7
18:57:15 web.1  |   Program Load (2.6ms)  SELECT "programs".* FROM "programs" WHERE "programs"."is_deleted" = 'f' AND "programs"."id" IN (1340, 711, 5, 1380, 1344, 1311, 1210)
18:57:15 web.1  | Cache read: views/episodes/149768-20140419064643365309000/episodes/149752-20140419064643075387000/episodes/149748-20140419064642994891000/episodes/149740-20140419064642741006000/episodes/149738-20140419064642706457000/episodes/149736-20140419064642673073000/episodes/149726-20140419064642492558000/6c2638ad89493f0c3e448b3d66c4a1de
18:57:15 web.1  | Read fragment views/episodes/149768-20140419064643365309000/episodes/149752-20140419064643075387000/episodes/149748-20140419064642994891000/episodes/149740-20140419064642741006000/episodes/149738-20140419064642706457000/episodes/149736-20140419064642673073000/episodes/149726-20140419064642492558000/6c2638ad89493f0c3e448b3d66c4a1de (0.6ms)
18:57:15 web.1  |   Episode Load (3.5ms)  SELECT "episodes".* FROM "episodes" WHERE "episodes"."is_deleted" = 'f' AND "episodes"."episode_type_id" = 1 ORDER BY "episodes"."id" DESC LIMIT 12
18:57:15 web.1  |   Program Load (2.6ms)  SELECT "programs".* FROM "programs" WHERE "programs"."is_deleted" = 'f' AND "programs"."id" IN (1016, 341)
18:57:15 web.1  | Cache read: views/episodes/149773-20140419094829793071000/episodes/149772-20140419091743738305000/episodes/149771-20140419091322119681000/episodes/149770-20140419100721271419000/episodes/149761-20140419064643243075000/episodes/149760-20140419064643225958000/episodes/149759-20140419064643207847000/episodes/149758-20140419064643182828000/episodes/149757-20140419064643166963000/episodes/149756-20140419064643149717000/episodes/149755-20140419064643132085000/episodes/149754-20140419064643113035000/6c2638ad89493f0c3e448b3d66c4a1de
18:57:15 web.1  | Read fragment views/episodes/149773-20140419094829793071000/episodes/149772-20140419091743738305000/episodes/149771-20140419091322119681000/episodes/149770-20140419100721271419000/episodes/149761-20140419064643243075000/episodes/149760-20140419064643225958000/episodes/149759-20140419064643207847000/episodes/149758-20140419064643182828000/episodes/149757-20140419064643166963000/episodes/149756-20140419064643149717000/episodes/149755-20140419064643132085000/episodes/149754-20140419064643113035000/6c2638ad89493f0c3e448b3d66c4a1de (0.6ms)

它会写入和读取缓存片段，但每次刷新页面时它都会运行所有 SQL！在我所有的刷新之后，日志总是相同的。它应该在第一次加载后只显示片段读数？？

我尝试重新安装 Dalli gem，将 memcached 升级到最新版本。

当我尝试在控制台中缓存和获取数据时，它是成功的。缓存也适用于生产环境。

我正在使用mini_profiler 在开发环境中查看 SQL 事务，并且我在 mini_profiler 弹出窗口中也看到了相同的 SQL...

你有什么想法吗？怎么回事？

我的视图文件的一部分：

<% cache @latest_episodes do %>
<% @latest_episodes.each do |t| %>
<% cache(t) do %>
<%= render 'common/slider_item', episode: t, lazy_owl: true %>
<% end %>
<% end %>
<% end %>

【问题讨论】：

执行此操作的代码是什么样的？
假设您在我的视图文件中询问代码，这是更新问题中的一部分

标签： ruby-on-rails caching memcached dalli

【解决方案1】：

我对这个问题还不是很清楚，但我已经找到了原因。

正如我在问题中所说，我在我的观点中使用的代码是这样的：

<% cache @latest_episodes do %>
<% @latest_episodes.each do |t| %>
<% cache(t) do %>
<%= render 'common/slider_item', episode: t, lazy_owl: true %>
<% end %>
<% end %>
<% end %>

当我将实例变量更改为常规字符串键并删除 cache(t) 块时，一切正常。

我猜这个问题的发生是因为 Rails 必须通过处理实例变量在每个请求上重新创建缓存键。但如果这是重点，为什么 Rails 也有自动过期机制呢？我猜的语句表明它应该总是命中数据库来创建缓存键。

如有任何意见，我们将不胜感激。

【讨论】：