为啥 Rails 渲染视图如此缓慢？
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【中文标题】为啥 Rails 渲染视图如此缓慢？【英文标题】：Why does Rails render the views so slowly?为什么 Rails 渲染视图如此缓慢？ 【发布时间】：2014-03-25 16:24:23 【问题描述】：使用 Rails 4 和 Ruby 1.9.3。 我在我正在渲染的 usuarios#show 中有这个视图。控制器需要大量数据，但我已经设法将使用 eager_load 和 akin 的查询从 300 毫秒（奇数）减少到 44 毫秒。
我的问题是数据库调用没问题，但是视图需要将近 30 秒才能呈现。
我已确保从控制器变量中获取我使用的所有内容。
编辑：我已经从控制器添加了查询本身
这是控制器方法，使用 eager_loading
#app/controllers/usuarios_controller.rb
before_action :show_usuario, only: [:show]
def show
if !@usuario.country_id.blank?
@country = @usuario.country
end
respond_to do |format
format.html
format.js
end
end
private
def show_usuario
if usuario_signed_in?
id = current_usuario.id
@usuario = Usuario.eager_load(:profile).find(id)
else
@usuario = Usuario.eager_load(:profile, textos: [:likes, :text_medals, :tags]).find(params[:id])
end
@textos = Texto.eager_load(:likes, :text_medals, :tags).where(:usuario_id => @usuario.id).order("textos.created_at DESC").paginate(:page => params[:page]).per_page(6)
end
这是我的日志
Started GET "/" for 127.0.0.1 at 2014-03-25 12:55:39 +0100
Usuario Load (1.4ms) SELECT "usuarios".* FROM "usuarios" WHERE "usuarios"."id" = 12 ORDER BY "usuarios"."id" ASC LIMIT 1
Processing by UsuariosController#show as HTML
Notification Load (1.2ms) SELECT "notifications".* FROM "notifications" INNER JOIN "textos" ON "textos"."id" = "notifications"."text" WHERE (textos.usuario_id = 12 AND notifications.user_related != 12) ORDER BY "notifications"."id" DESC LIMIT 10
SQL (1.2ms) SELECT "usuarios"."id" AS t0_r0, "usuarios"."email" AS t0_r1, "usuarios"."encrypted_password" AS t0_r2, "usuarios"."reset_password_token" AS t0_r3, "usuarios"."reset_password_sent_at" AS t0_r4, "usuarios"."remember_created_at" AS t0_r5, "usuarios"."sign_in_count" AS t0_r6, "usuarios"."current_sign_in_at" AS t0_r7, "usuarios"."last_sign_in_at" AS t0_r8, "usuarios"."current_sign_in_ip" AS t0_r9, "usuarios"."last_sign_in_ip" AS t0_r10, "usuarios"."created_at" AS t0_r11, "usuarios"."updated_at" AS t0_r12, "usuarios"."nombre" AS t0_r13, "usuarios"."fecha_nac" AS t0_r14, "usuarios"."country_id" AS t0_r15, "usuarios"."is_admin" AS t0_r16, "usuarios"."publish_fbviews" AS t0_r17, "usuarios"."accept_terms" AS t0_r18, "profiles"."id" AS t1_r0, "profiles"."usuario_id" AS t1_r1, "profiles"."quote" AS t1_r2, "profiles"."quote_author" AS t1_r3, "profiles"."fb_account" AS t1_r4, "profiles"."twt_account" AS t1_r5, "profiles"."gpls_account" AS t1_r6, "profiles"."biografia" AS t1_r7, "profiles"."created_at" AS t1_r8, "profiles"."updated_at" AS t1_r9, "profiles"."hide_email" AS t1_r10, "profiles"."pic_file_name" AS t1_r11, "profiles"."pic_content_type" AS t1_r12, "profiles"."pic_file_size" AS t1_r13, "profiles"."pic_updated_at" AS t1_r14 FROM "usuarios" LEFT OUTER JOIN "profiles" ON "profiles"."usuario_id" = "usuarios"."id" WHERE "usuarios"."id" = $1 LIMIT 1 [["id", 12]]
USER CARGADO
Country Load (0.7ms) SELECT "countries".* FROM "countries" WHERE "countries"."id" = $1 LIMIT 1 [["id", 246]]
TEXTOS CARGADOS
Rendered usuarios/_main_frame.html.erb (12082.9ms)
(1.6ms) SELECT COUNT(DISTINCT "textos"."id") FROM "textos" LEFT OUTER JOIN "likes" ON "likes"."texto_id" = "textos"."id" LEFT OUTER JOIN "text_medals_textos" ON "text_medals_textos"."texto_id" = "textos"."id" LEFT OUTER JOIN "text_medals" ON "text_medals"."id" = "text_medals_textos"."text_medal_id" LEFT OUTER JOIN "tags_textos" ON "tags_textos"."texto_id" = "textos"."id" LEFT OUTER JOIN "tags" ON "tags"."id" = "tags_textos"."tag_id" WHERE "textos"."usuario_id" = 12
SQL (1.9ms) SELECT DISTINCT "textos".id, textos.created_at AS alias_0 FROM "textos" LEFT OUTER JOIN "likes" ON "likes"."texto_id" = "textos"."id" LEFT OUTER JOIN "text_medals_textos" ON "text_medals_textos"."texto_id" = "textos"."id" LEFT OUTER JOIN "text_medals" ON "text_medals"."id" = "text_medals_textos"."text_medal_id" LEFT OUTER JOIN "tags_textos" ON "tags_textos"."texto_id" = "textos"."id" LEFT OUTER JOIN "tags" ON "tags"."id" = "tags_textos"."tag_id" WHERE "textos"."usuario_id" = 12 ORDER BY textos.created_at DESC LIMIT 6 OFFSET 0
SQL (5.6ms) SELECT "textos"."id" AS t0_r0, "textos"."usuario_id" AS t0_r1, "textos"."titulo" AS t0_r2, "textos"."contenido" AS t0_r3, "textos"."idioma" AS t0_r4, "textos"."created_at" AS t0_r5, "textos"."updated_at" AS t0_r6, "textos"."is_borrador" AS t0_r7, "textos"."is_on_contest" AS t0_r8, "textos"."portada_file_name" AS t0_r9, "textos"."portada_content_type" AS t0_r10, "textos"."portada_file_size" AS t0_r11, "textos"."portada_updated_at" AS t0_r12, "textos"."contest_id" AS t0_r13, "textos"."views" AS t0_r14, "textos"."has_draft" AS t0_r15, "textos"."license_type" AS t0_r16, "likes"."id" AS t1_r0, "likes"."usuario_id" AS t1_r1, "likes"."texto_id" AS t1_r2, "likes"."created_at" AS t1_r3, "likes"."updated_at" AS t1_r4, "text_medals"."id" AS t2_r0, "text_medals"."name" AS t2_r1, "text_medals"."slogan" AS t2_r2, "text_medals"."created_at" AS t2_r3, "text_medals"."updated_at" AS t2_r4, "text_medals"."image_file_name" AS t2_r5, "text_medals"."image_content_type" AS t2_r6, "text_medals"."image_file_size" AS t2_r7, "text_medals"."image_updated_at" AS t2_r8, "tags"."id" AS t3_r0, "tags"."nombre" AS t3_r1, "tags"."created_at" AS t3_r2, "tags"."updated_at" AS t3_r3 FROM "textos" LEFT OUTER JOIN "likes" ON "likes"."texto_id" = "textos"."id" LEFT OUTER JOIN "text_medals_textos" ON "text_medals_textos"."texto_id" = "textos"."id" LEFT OUTER JOIN "text_medals" ON "text_medals"."id" = "text_medals_textos"."text_medal_id" LEFT OUTER JOIN "tags_textos" ON "tags_textos"."texto_id" = "textos"."id" LEFT OUTER JOIN "tags" ON "tags"."id" = "tags_textos"."tag_id" WHERE "textos"."usuario_id" = 12 AND "textos"."id" IN (75, 74, 73, 70, 69, 68) ORDER BY textos.created_at DESC
CACHE (0.0ms) SELECT COUNT(DISTINCT "textos"."id") FROM "textos" LEFT OUTER JOIN "likes" ON "likes"."texto_id" = "textos"."id" LEFT OUTER JOIN "text_medals_textos" ON "text_medals_textos"."texto_id" = "textos"."id" LEFT OUTER JOIN "text_medals" ON "text_medals"."id" = "text_medals_textos"."text_medal_id" LEFT OUTER JOIN "tags_textos" ON "tags_textos"."texto_id" = "textos"."id" LEFT OUTER JOIN "tags" ON "tags"."id" = "tags_textos"."tag_id" WHERE "textos"."usuario_id" = 12
Usuario Load (0.8ms) SELECT "usuarios".* FROM "usuarios" WHERE "usuarios"."id" = $1 ORDER BY "usuarios"."id" ASC LIMIT 1 [["id", 12]]
Profile Load (0.7ms) SELECT "profiles".* FROM "profiles" WHERE "profiles"."usuario_id" = $1 ORDER BY "profiles"."id" ASC LIMIT 1 [["usuario_id", 12]]
CACHE (0.1ms) SELECT "usuarios".* FROM "usuarios" WHERE "usuarios"."id" = $1 ORDER BY "usuarios"."id" ASC LIMIT 1 [["id", 12]]
CACHE (0.0ms) SELECT "profiles".* FROM "profiles" WHERE "profiles"."usuario_id" = $1 ORDER BY "profiles"."id" ASC LIMIT 1 [["usuario_id", 12]]
CACHE (0.1ms) SELECT "usuarios".* FROM "usuarios" WHERE "usuarios"."id" = $1 ORDER BY "usuarios"."id" ASC LIMIT 1 [["id", 12]]
CACHE (0.0ms) SELECT "profiles".* FROM "profiles" WHERE "profiles"."usuario_id" = $1 ORDER BY "profiles"."id" ASC LIMIT 1 [["usuario_id", 12]]
CACHE (0.1ms) SELECT "usuarios".* FROM "usuarios" WHERE "usuarios"."id" = $1 ORDER BY "usuarios"."id" ASC LIMIT 1 [["id", 12]]
CACHE (0.1ms) SELECT "profiles".* FROM "profiles" WHERE "profiles"."usuario_id" = $1 ORDER BY "profiles"."id" ASC LIMIT 1 [["usuario_id", 12]]
CACHE (0.0ms) SELECT "usuarios".* FROM "usuarios" WHERE "usuarios"."id" = $1 ORDER BY "usuarios"."id" ASC LIMIT 1 [["id", 12]]
CACHE (0.0ms) SELECT "profiles".* FROM "profiles" WHERE "profiles"."usuario_id" = $1 ORDER BY "profiles"."id" ASC LIMIT 1 [["usuario_id", 12]]
CACHE (0.1ms) SELECT "usuarios".* FROM "usuarios" WHERE "usuarios"."id" = $1 ORDER BY "usuarios"."id" ASC LIMIT 1 [["id", 12]]
CACHE (0.1ms) SELECT "profiles".* FROM "profiles" WHERE "profiles"."usuario_id" = $1 ORDER BY "profiles"."id" ASC LIMIT 1 [["usuario_id", 12]]
Rendered usuarios/_user_texts.html.erb (16760.5ms)
Rendered usuarios/show.html.erb within layouts/application (28889.5ms)
Completed 200 OK in 29246ms (Views: 28898.8ms | ActiveRecord: 44.1ms)
如您所见，视图需要很长时间才能呈现。 这是“_user_texts”部分。
<div class="ui grid">
<% @textos.each do |texto| %>
<div class="text row" text-pages="<%= @textos.total_pages%>">
<div class="five wide column">
<%= image_tag texto.portada.url(:medium), :class => "ui rounded medium left floated image text-cover" %>
</div>
<div class="eleven wide column">
<div class="row">
<h1 class="ui header">
<%= link_to text_name(texto), usuario_texto_path(texto.usuario.id, texto.id), :class => "title-format"%>
<div class="sub header subheader-format">
escrito por <%= text_author_image texto %><%= text_author_name texto %> el <%= humanize_creation_date(texto.created_at) %>
</div>
</h1>
</div>
<div class="tag-list row">
<div class="ui horizontal list">
<% if not texto.tags.empty? %>
<% texto.tags.each do |tag| %>
<div class="tag item">
<%= link_to tag.nombre, tag_path(tag.id), :class => "ui red large label" %>
</div>
<% end %>
<% end %>
</div>
</div>
</div>
</div>
<% end %>
</div>
<% if @textos.total_pages > @textos.current_page %>
<a id="more_texts" href="javascript:void(0)">
<span class="vertical"></span><span>Ver más</span>
</a>
<% end %>
编辑：我正在使用分页。特别是will_paginate gem。当我到达页面底部时，有一个用于获取更多结果的按钮。
有人可以告诉我如何让它更快吗？这让我发疯了。 谢谢！
【问题讨论】：
可能与this Carrierwave issue有关。你可以在没有图像的情况下尝试它，看看它是否恢复正常？可能值得与 Github 上的维护人员联系，以便他们可以重新打开问题（它看起来从未修复过）。@textos 变量保存了多少条记录？ texto.tags 平均保存多少条记录？我建议去掉 usuarios/_user_texts.html.erb 部分，直到你到达最慢的部分。
@ZachKemp 我正在使用回形针。
我相信你需要使用 kaminari 之类的东西来为你的文本分页，而不是在页面上加载所有这些东西。
我会对您的查询进行基准测试，对我来说似乎很重。我认为重点应该放在提高 sql 查询的性能上。我不知道确切的内容，但我怀疑您是否需要在一个查询中获得这么多的情报。
【参考方案1】：
我会对您的查询进行基准测试，这对我来说似乎很重。我认为重点应该放在提高 sql 查询的性能上。我不知道确切的内容，但我怀疑您是否需要在一个查询中获得这么多的情报。
例如，您可以在表中添加索引以提高性能。您还应该考虑您真正需要的属性并使用 select 来定义它们。查询中的列越少，结果就越快。
最后，你做了很多连接。看起来您几乎加入了所有模型。左连接真的很慢，因为你会遍历所有记录。如果您真的需要所有这些连接，那么如果您可以将其中一些左连接转换为内部连接，那就太好了。这将意味着巨大的改进，因为您只需检查相关记录。
【讨论】：
感谢您的见解。我将阅读有关内部连接的信息，听起来不错。 如果您在开篇文章中显示您的查询将会很有用。现在我们看到了所有的 sql 输出，阅读起来不太友好。尤其是在手机上。 :)【参考方案2】：在您在视图中调用 .all 或 .each 之前，查询不会真正运行，即使您将结果存储在控制器中的实例变量中也是如此。这可能会使视图看起来很慢，而实际上它是数据库中的内容。
尝试调用一些调用来对视图中的不同位置进行基准测试，以查看时间在哪里使用。
http://api.rubyonrails.org/classes/ActiveSupport/Benchmarkable.html#method-i-benchmark
为了查看您正在查询的内容并发现缺失的索引等。解释很方便。
http://guides.rubyonrails.org/active_record_querying.html#running-explain
【讨论】：
不知道第一部分。我会调查的。谢谢！【参考方案3】：解决了。在 Bullet gem 的帮助下，我重新制定了我渴望加载的方式。
事实证明，实际上所做的一切都做得很好。问题是我的搭档将回形针的图像存储在 Dropbox 中。 Dropbox 很可能不是针对此类请求的，所以延迟就是因为这个。我们将改用亚马逊的 S3。
对于未来的读者：请注意！并检查您将图像存储在哪里。
谢谢大家！
【讨论】：
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