EmbedView - easy way to improve by 5-20% performance

Improve application performance by 5-20% (depending on your logic, views and layouts) without major code changes.

Rails have slow rendering, expecially when you have view and many partials included inside.

This gem simply embeds views into another views. Works similar to partials, but instead of rendering main view, partials - it's creates a bigger view with content from partials and renders all together.

So if you have a pretty stable app, rarely changed ERB views(_header, _footer, _modal, _ga, _sharethis, _etc...) you can embed them in main view/layout and render together.

Such small tweak could give 5-20% boost for performance.

Usage

Currently works only with ERB templates.

Instead of:

  <%= render '/shared/header' %>

just write:

  <%= embed_view "../shared/_header.html.erb" %>

Please note that this is not a typical helper. This is just a meta tag which will be replaced with content from file.

There are no familiar "locals", "collection", etc things from "partial".

During development just follow the rule that content from embedded file is inside this file. So all variables available before embed_view will be available in inserted file.

Path to file must be relative to file where it's embeds.

Note: Only this is correct syntax <%= embed_view "../shared/_header.html.erb" %>. Specify relative path to file with real filename.

Installation

Add this line to your application's Gemfile:

gem 'embed_view'

And then execute:

$ bundle

Or install it yourself as:

$ gem install embed_view

Sample

https://boiling-falls-90100.herokuapp.com/ - simple app without this gem, typical to many apps (code https://github.com/BogdanBusko/erb_test)

https://erbtest2.herokuapp.com/ - the same app but with this gem (code https://github.com/BogdanBusko/erb_test/tree/add-embed-view)

Another sample of rendering from dummy app: https://github.com/igorkasyanchuk/embed_view/tree/master/test/dummy/app/views

Processing by UsersController#show as HTML
  Parameters: {"id"=>"6"}
  User Load (0.2ms)  SELECT  "users".* FROM "users" WHERE "users"."id" = ? LIMIT ?  [["id", 6], ["LIMIT", 1]]
  ↳ app/controllers/users_controller.rb:51
  embed_view: ../shared/_header.html.erb
  embed_view: ../shared/_footer.html.erb
  embed_view: _ga.html.erb
  Rendering users/show.html.erb within layouts/application
  Rendered users/show.html.erb within layouts/application (0.9ms)
   (0.1ms)  SELECT COUNT(*) FROM "users"
  ↳ app/views/layouts/application.html.erb:20
  User Load (0.2ms)  SELECT  "users".* FROM "users" ORDER BY random() LIMIT ?  [["LIMIT", 5]]
  ↳ app/views/layouts/application.html.erb:428
Completed 200 OK in 38ms (Views: 34.9ms | ActiveRecord: 0.5ms)

Before

  <tbody>
    <% @users.each do |user| %>
      <%= render '/users/user', user: user %>
    <% end %>
  </tbody>

After (see that no variables are passed, because "user" variable is already defined)

  <tbody>
    <% @users.each do |user| %>
      <%= embed_view "_user.html.erb" %>
    <% end %>
  </tbody>

Known issues & limitations

support only ERB
if you have an issue in code in embedded file you won't see correct line with error
not tested with older Rails (only with Rails 5.2)

TODO

better readme with many samples
SLIM support
HAML support
verify how it works with AJAX requests
support older Rails
show line with error in code if crash in ERB
check regexp in code if it's good and fast
think about better logging
other file types support
absolute path (using Rails.root)
more tests (check that content from partials was rendered)
travis.ci
compare numbers(benchmark), visualize in readme
mention in readme links to 2 stagings + source code on heroku
reame in samples apps with link to heroku

Benchmarking

wrk -t2 -c2 -d10s http://localhost:3000

Contributing

You are welcome to contribute.

Contributors:

https://github.com/BogdanBusko - created samples, heroku apps and benchmarked them

License

The gem is available as open source under the terms of the MIT License.