Diagnosing the cause of slow view rendering

Ruby on-Rails

Ruby on-Rails Problem Overview

I'm not sure when this started, but something unusual is happening in my app (run locally on a development machine). Suddenly I am seeing messages like:

Started GET "/" for 127.0.0.1 at 2013-03-10 12:10:24 +1300
Processing by PagesController#home as HTML
  Rendered pages/home.html.erb within layouts/application (2.4ms)
Completed 200 OK in 3242ms (Views: 3241.4ms | ActiveRecord: 0.0ms)

As you can see 3 seconds to load the home page (a relatively simple page) ... We're not talking a hard page reload .. just clicking on the "home" link again from another page.

Not really sure where to start here, but this is my application.rb:

#config/boot.rb is loaded
require File.expand_path('../boot', __FILE__)

require 'rails/all'

if defined?(Bundler)
  Bundler.require(*Rails.groups(:assets => %w(development test)))
end

module Goodsounds
  class Application < Rails::Application
    config.encoding = "utf-8"
    config.filter_parameters += [:password]
	config.assets.initialize_on_precompile = false
    config.assets.enabled = true
    config.action_controller.assets_dir = "#{File.dirname(File.dirname(__FILE__))}/public"
    config.assets.version = '1.0'
    config.autoload_paths += Dir["#{Rails.root}/lib/modules"]
    config.assets.paths += Dir["#{Rails.root}/app/assets/fonts/*"]
    config.assets.precompile += %w( .svg .eot .woff .ttf ) 
  end
end

...and dev.rb:

Goodsounds::Application.configure do
  # Settings specified here will take precedence over those in config/application.rb
	Paperclip.options[:command_path] = "/usr/bin/"
	
	config.action_mailer.default_url_options = { :host => 'localhost:3000' }

  config.action_mailer.raise_delivery_errors = true

  # set delivery method to :smtp, :sendmail or :test
  config.action_mailer.delivery_method = :smtp

  # these options are only needed if you choose smtp delivery

  config.action_mailer.smtp_settings = { :address => "localhost", :port => 1025 }

  # In the development environment your application's code is reloaded on
  # every request. This slows down response time but is perfect for development
  # since you don't have to restart the web server when you make code changes.
  config.cache_classes = false

  # Log error messages when you accidentally call methods on nil.
  config.whiny_nils = true

  # Show full error reports and disable caching
  config.consider_all_requests_local       = true
  config.action_controller.perform_caching = false

  # Print deprecation notices to the Rails logger
  config.active_support.deprecation = :log

  # Only use best-standards-support built into browsers
  config.action_dispatch.best_standards_support = :builtin

  # Raise exception on mass assignment protection for Active Record models
  config.active_re
cord.mass_assignment_sanitizer = :strict

  # Log the query plan for queries taking more than this (works
  # with SQLite, MySQL, and PostgreSQL)
  config.active_record.auto_explain_threshold_in_seconds = 0.5

  # Do not compress assets
  config.assets.compress = false

  # Expands the lines which load the assets
  config.assets.debug = true
end

EDIT:

OK, Here is what I am seeing on new relic. Doesn't really help me though. Any thoughts?

enter image description here

enter image description here

Oh and what I learned from Chrome timeline:

Send Request - Details
Duration	0 (at 655 ms)
Resource	localhost
Request Method	GET

Receive Response - Details
Duration	0.043 ms (at 4.17 s)
Resource	localhost
Status Code	200
MIME Type	text/html

Receive Data - Details
Duration	176.329 ms (at 4.17 s)
Self Time	7.037 ms
CPU Time	176.329 ms
Aggregated Time	061.194 ms114.664 ms0.471 ms0
Resource	localhost
Encoded Data Length	303 Bytes
Used Heap Size	29.1 MB (+5.7 MB)

Finish Loading - Details
Duration	0 (at 4.35 s)
Resource	localhost

By the way I disabled the quiet_assets gem to see what I could discover in the terminal.. again.. not helpful:

Started GET "/" for 127.0.0.1 at 2013-03-10 21:46:40 +1300
Processing by PagesController#home as HTML
  Rendered pages/home.html.erb within layouts/application (43.4ms)
Completed 200 OK in 3501ms (Views: 3480.9ms | ActiveRecord: 19.4ms)


Started GET "/assets/dataTables/jquery.dataTables.bootstrap.css?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /dataTables/jquery.dataTables.bootstrap.css - 304 Not Modified (11ms)


Started GET "/assets/chosen.css?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /chosen.css - 304 Not Modified (5ms)


Started GET "/assets/select2.css?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /select2.css - 304 Not Modified (4ms)


Started GET "/assets/autocomplete.css?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /autocomplete.css - 304 Not Modified (1ms)


Started GET "/assets/branches.css?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /branches.css - 304 Not Modified (2ms)


Started GET "/assets/bubbles.css?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /bubbles.css - 304 Not Modified (1ms)


Started GET "/assets/business_show.css?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /business_show.css - 304 Not Modified (1ms)


Started GET "/assets/chunkyfive_font.css?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /chunkyfive_font.css - 304 Not Modified (1ms)


Started GET "/assets/consumer_show.css?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /consumer_show.css - 304 Not Modified (2ms)


Started GET "/assets/datatable_styling.css?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /datatable_styling.css - 304 Not Modified (1ms)


Started GET "/assets/datepicker.css?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /datepicker.css - 304 Not Modified (2ms)


Started GET "/assets/devise_links.css?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /devise_links.css - 304 Not Modified (1ms)


Started GET "/assets/dispenser_show.css?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /dispenser_show.css - 304 Not Modified (1ms)


Started GET "/assets/fonts.css?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /fonts.css - 304 Not Modified (1ms)


Started GET "/assets/forms.css?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /forms.css - 304 Not Modified (2ms)


Started GET "/assets/gmaps4rails.css?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /gmaps4rails.css - 304 Not Modified (1ms)


Started GET "/assets/jquery-ui-1.10.0.custom.css?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /jquery-ui-1.10.0.custom.css - 304 Not Modified (2ms)


Started GET "/assets/jumbotrons.css?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /jumbotrons.css - 304 Not Modified (1ms)


Started GET "/assets/layout.css?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /layout.css - 304 Not Modified (1ms)


Started GET "/assets/open_sans.css?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /open_sans.css - 304 Not Modified (2ms)


Started GET "/assets/popover.css?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /popover.css - 304 Not Modified (1ms)


Started GET "/assets/reviews.css?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /reviews.css - 304 Not Modified (1ms)


Started GET "/assets/spinner.css?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /spinner.css - 304 Not Modified (2ms)


Started GET "/assets/style_show.css?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /style_show.css - 304 Not Modified (2ms)


Started GET "/assets/style_show_reviews.css?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /style_show_reviews.css - 304 Not Modified (2ms)


Started GET "/assets/jquery.js?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /jquery.js - 304 Not Modified (3ms)


Started GET "/assets/jquery_ujs.js?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /jquery_ujs.js - 304 Not Modified (3ms)


Started GET "/assets/ui.custom.min.js?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /ui.custom.min.js - 304 Not Modified (1ms)


Started GET "/assets/bootstrap-transition.js?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /bootstrap-transition.js - 304 Not Modified (5ms)


Started GET "/assets/bootstrap-affix.js?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /bootstrap-affix.js - 304 Not Modified (3ms)


Started GET "/assets/bootstrap-alert.js?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /bootstrap-alert.js - 304 Not Modified (4ms)


Started GET "/assets/bootstrap-button.js?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /bootstrap-button.js - 304 Not Modified (5ms)


Started GET "/assets/bootstrap-carousel.js?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /bootstrap-carousel.js - 304 Not Modified (3ms)


Started GET "/assets/bootstrap-collapse.js?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /bootstrap-collapse.js - 304 Not Modified (3ms)


Started GET "/assets/bootstrap-dropdown.js?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /bootstrap-dropdown.js - 304 Not Modified (3ms)


Started GET "/assets/bootstrap-modal.js?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /bootstrap-modal.js - 304 Not Modified (3ms)


Started GET "/assets/bootstrap-scrollspy.js?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /bootstrap-scrollspy.js - 304 Not Modified (3ms)


Started GET "/assets/bootstrap-tab.js?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /bootstrap-tab.js - 304 Not Modified (3ms)


Started GET "/assets/bootstrap-tooltip.js?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /bootstrap-tooltip.js - 304 Not Modified (5ms)


Started GET "/assets/bootstrap-popover.js?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /bootstrap-popover.js - 304 Not Modified (52ms)


Started GET "/assets/bootstrap-typeahead.js?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /bootstrap-typeahead.js - 304 Not Modified (3ms)


Started GET "/assets/bootstrap.js?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /bootstrap.js - 304 Not Modified (13ms)


Started GET "/assets/gmaps4rails/gmaps4rails.base.js?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /gmaps4rails/gmaps4rails.base.js - 304 Not Modified (1ms)


Started GET "/assets/gmaps4rails/gmaps4rails.bing.js?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /gmaps4rails/gmaps4rails.bing.js - 304 Not Modified (2ms)


Started GET "/assets/gmaps4rails/gmaps4rails.googlemaps.js?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /gmaps4rails/gmaps4rails.googlemaps.js - 304 Not Modified (2ms)


Started GET "/assets/gmaps4rails/gmaps4rails.mapquest.js?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /gmaps4rails/gmaps4rails.mapquest.js - 304 Not Modified (2ms)


Started GET "/assets/gmaps4rails/gmaps4rails.openlayers.js?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /gmaps4rails/gmaps4rails.openlayers.js - 304 Not Modified (2ms)


Started GET "/assets/jqueryplugins/addresspicker.js?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /jqueryplugins/addresspicker.js - 304 Not Modified (2ms)


Started GET "/assets/jqueryplugins/browser_detect.js?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /jqueryplugins/browser_detect.js - 304 Not Modified (3ms)


Started GET "/assets/jqueryplugins/charts.js?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /jqueryplugins/charts.js - 304 Not Modified (2ms)


Started GET "/assets/jqueryplugins/jquery.alphanumeric.js?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /jqueryplugins/jquery.alphanumeric.js - 304 Not Modified (1ms)


Started GET "/assets/jqueryplugins/jquery.formrestrict.js?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /jqueryplugins/jquery.formrestrict.js - 304 Not Modified (2ms)


Started GET "/assets/jqueryplugins/jquery.lazyload.js?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /jqueryplugins/jquery.lazyload.js - 304 Not Modified (1ms)


Started GET "/assets/jqueryplugins/raty.js?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /jqueryplugins/raty.js - 304 Not Modified (2ms)


Started GET "/assets/dataTables/jquery.dataTables.js?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /dataTables/jquery.dataTables.js - 304 Not Modified (13ms)


Started GET "/assets/dataTables/jquery.dataTables.bootstrap.js?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /dataTables/jquery.dataTables.bootstrap.js - 304 Not Modified (63ms)


Started GET "/assets/lib/abstract-chosen.js?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /lib/abstract-chosen.js - 304 Not Modified (12ms)


Started GET "/assets/lib/select-parser.js?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /lib/select-parser.js - 304 Not Modified (12ms)


Started GET "/assets/chosen.jquery.js?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /chosen.jquery.js - 304 Not Modified (8ms)


Started GET "/assets/chosen-jquery.js?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /chosen-jquery.js - 304 Not Modified (9ms)


Started GET "/assets/select2.js?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /select2.js - 304 Not Modified (7ms)


Started GET "/assets/highcharts.js?body=1" for 127.0.0.1 at 2013-03-10 21:46:44 +1300
Served asset /highcharts.js - 304 Not Modified (1ms)

By the way, as per a suggestion on reddit I precompiled assets and ran the server. Seeing fantastic speeds:

Processing by PagesController#home as HTML
Rendered pages/home.html.erb within layouts/application (1.1ms)
Completed 200 OK in 6ms (Views: 5.4ms | ActiveRecord: 0.0ms)

Ok not sure this is providing any help or not but the major delay is happening between these two lines of code in the stack:

From: /home/funkdified/.rvm/gems/ruby-1.9.3-p392@goodsounds/gems/actionpack-3.2.13.rc1/lib/action_controller/metal/implicit_render.rb @ line 5 ActionController::ImplicitRender#send_action:

    3: def send_action(method, *args)
    4:   ret = super
 => 5:   default_render unless response_body
    6:   ret
    7: end

[2] pry(#<PagesController>)> next

MAJOR DELAY

From: /home/funkdified/.rvm/gems/ruby-1.9.3-p392@goodsounds/gems/actionpack-3.2.13.rc1/lib/action_controller/metal/implicit_render.rb @ line 6 ActionController::ImplicitRender#send_action:

    3: def send_action(method, *args)
    4:   ret = super
    5:   default_render unless response_body
 => 6:   ret
    7: end

Ruby on-Rails Solutions

Solution 1 - Ruby on-Rails

Ok, I figured it out (at long last). Without changing any of my actual assets I am now seeing this is development:

Started GET "/" for 127.0.0.1 at 2013-03-11 23:14:33 +1300
Processing by PagesController#home as HTML
Rendered pages/home.html.erb within layouts/application (1.3ms)

It turns out the delay was being caused by config.assets.debug = true inside of development.rb. Setting this to false resolves the problem.

Looks like the Rails core team debated turning this off by default, but decided against the idea. In the future I'd love to see them put something in the comment section of development.rb to tip off users of the potential for significant delays.

May I suggest the following:

# Expands the lines which load the assets 
# May cause significant delays in view rendering

Great, they heard me muttering and updated rails!

Solution 2 - Ruby on-Rails

The same issue has appeared for me in rails 4.1+. Abram's answer is only partially complete.

You can leave config.assets.debug = true but should disable new assets verification feature

# Adds additional error checking when serving assets at runtime.
# Checks for improperly declared sprockets dependencies.
# Raises helpful error messages.
config.assets.raise_runtime_errors = false

Solution with config.assets.debug disabled only works because it compiles assets once and assets are verified once. Assets verification is where the most of the time is spent.

Solution 3 - Ruby on-Rails

If you're coming from rails 3.2.13 note that a bunch of people have experienced this issue and reverting to 3.2.12 seems to resolve it. You can find more info here on github.

In my case disabling config.assets.debug sped things up a little, but reverting to 3.2.12 dropped request time from around 4 seconds to around 250ms.

Solution 4 - Ruby on-Rails

Take a look at NewRelic.com - it costs, but the free trial will allow you to totally dissect your application and work out where any bottlenecks are.

Aside from New Relic run through the usual checks, e.g. when did it start? What have you changed recently? Have you upgraded Rails and/or any gems? Check out and run a few previous versions from your source control and try and work out specifically which commit caused the issue.

Does the issue happen with all browsers? Try firing up the Chrome timeline viewer and you'll be able to see if the browser is getting stuck up on a particular piece of JavaScript.

Also try switching your local dev web server to thin, does the issue persist?

Good luck!

Solution 5 - Ruby on-Rails

Are you on OSX and serving via .local?

If so, gonna throw the post I found in my comments as a solution:
https://stackoverflow.com/questions/13256485/subdomain-constraint-rails-3-makes-local-server-thin-so-slow

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Attributions

All content for this solution is sourced from the original question on Stackoverflow.

The content on this page is licensed under the Attribution-ShareAlike 4.0 International (CC BY-SA 4.0) license.

Content TypeOriginal AuthorOriginal Content on Stackoverflow
QuestionAbramView Question on Stackoverflow
Solution 1 - Ruby on-RailsAbramView Answer on Stackoverflow
Solution 2 - Ruby on-RailsAnton KView Answer on Stackoverflow
Solution 3 - Ruby on-RailsSean O'HaraView Answer on Stackoverflow
Solution 4 - Ruby on-RailsDaveStephensView Answer on Stackoverflow
Solution 5 - Ruby on-RailsjemmingerView Answer on Stackoverflow