Getting the most out of your Ruby on Rails applications: from zero to hero

Getting the most of your
applications

Ruby on
Rails

Getting the most of your
applications

Web

my dad
is at
about.me/

left right

I HAVE A AND I HAVE A
DAY JOB NIGHT JOB

program
ming
DON’T
language SCALE
s .

unless your website
is
HELLO
WORLD

<
PROGRAMMING LANGUAGE
APPLICATION ARCHITECTURE

request-log-analyzer
github.com/wvanbergen/request-log-analyzer

EE
so you have no reason not to
monitor your application

proﬁle
everyth
ing

ruby-prof
github.com/rdp/ruby-prof

perftools.rb
github.com/tmm1/perftools.rb

rack-
perftools_proﬁler
github.com/bhb/rack-perftools_proﬁler

queries queries queries queries
queries

LET RAILS DO ITS JOB
t.references

class Subscription < ActiveRecord::Base
  belongs_to :user
  belongs_to :follower
end

class User < ActiveRecord::Base
  has_many :subscriptions_from
  has_many :subscriptions_to

  has_one :avatar
  has_one :background

  has_many :update
  has_one :current_update
end

A QUERY THAT
FETCHES IT ALL
LET’S DO THE MATH

@subscriptions = Subsciption.where(
"`user_id` = ? OR `follower_id` = ?", @user.id, @user.id
)

2030 SUBSCRIPTIONS
+ 2030 * 2 USERS
+ 2030 * 2 AVATARS
+ 2030 * 2 BACKGROUNDS
+ 2030 * CURRENT UPDATES
= 16241 QUERIES

LET’S USE
include
@subscriptions = Subsciption.where(
  "`user_id` = ? OR `follower_id` = ?", @user.id, @user.id
).include({
  :user => [:avatar, :background, :current_status],
  :follower => [:avatar, :background, :current_status]
})

2030 SUBSCRIPTIONS
+ 2030 * 2 USERS
+ 2030 * 2 AVATARS
+ 2030 * 2 BACKGROUNDS
+ 2030 * CURRENT UPDATES
= 5 QUERIES

bullet
github.com/ﬂyerhzm/bullet

HTTP CACHING
IS ALWAYS BETTER
THAN APPLICATION
CACHING

NO CODE THAT YOU
WRITE
IS FASTER
THAN NO CODE



   













   





 





 



CACHING IN RAILS

PAGE
ACTION
FRAGMENT

IN GENERAL
CACHE EXPIRATION IS
HARD

THERE ARE ONLY
TWO HARD THINGS
IN COMPUTER
SCIENCE: CACHE
INVALIDATION AND
NAMING THINGSyou’ve never seen this,
right? :-)

WHAT IF YOU DIDN’T
HAVE TO
EXPIRE CACHE?

<%= cache @record do %>
  <div>
    <%= @record.expensive_to_render %>
  </div>
<% end %>

CACHE KEY:
RECORD/
1-123456789123

LET KEYS AUTO-
EXPIRE
WITH LRU
USE MEMCACHED,
REDIS & OTHERS

WOULD YOU RATHER
WASTE SOME
MEMORY?

OR WOULD YOU
RATHER WASTE
HOURS OF CODING?

AND YOU CAN EXPIRE
RELATED OBJECTS
WITH
touch

WILL YOU EVER USE
PAGE CACHING? OR
ACTION CACHING?

YOU MIGHT.

Buy I don’t recommend.

USE VARNISH
FETCH WITH
JAVASCRIPT

USE VARNISH
PROCESS WITH
JAVASCRIPT

YOU ARE USING C
EXTENSIONS
ALREADY!

IT’S EASY TO WRITE C
EXTENSIONS
if you know C, that is!

MOST C EXTENSIONS
REQUIRE A LINE IN
GEMFILE

home_run
github.com/jeremyevans/home_run

07/MAY/
2012:06:26:56
+0200
* 1 000 000

nokogiri
github.com/tenderlove/nokogiri

hiredis
github.com/pietern/hiredis-rb

IT’S HARD TO WRITE
C EXTENSIONS

background everyth
process
ing

delayed_job
github.com/collectiveidea/delayed_job

resque
github.com/defunkt/resque

sidekiq
github.com/mperham/sidekiq

Rails.queue

In Ruby on Rails 4, due...

the smallest rails app
thesmallestrailsapp.com

%w(action_controller/railtie coderay).map &method(:require)

run TheSmallestRailsApp ||= Class.new(Rails::Application) {
  config.secret_token = routes.append { root to: 'hello#world' }.inspect
  initialize!
}

class HelloController < ActionController::Base
  def world
    render inline: "
<!DOCTYPE html>
<title>The Smallest Rails App</title>
<h3>I am the smallest rails app!</h3>
<p>Here is my source code:</p>
#{CodeRay.scan_file(__FILE__, :ruby).div(line_numbers: :table)}
<a href='https://github.com/artemave/thesmallestrailsapp.com'>Small!</a>
"
  end
end

QUESTIONS?
https://joind.in/6473

Getting the most out of your Ruby on Rails applications: from zero to hero

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