Improving Your Heroku App Performance with Asset CDN and Unicorn

Optimizing rails applications’
performance
with Asset CDN and Unicorn

Simon Bagreev, @status_200
sbagreev@gmail.com

Friday, January 11, 13

Question
Does anyone know what

f5dd
is?


What This Preso is NOT

• not a coding demo or tutorial (strangely)
• not a best practices showcase


What This Preso IS

• tips and tricks on tuning rails application
• personal experience


Disclaimer
There are many other ways to improve app’s performance:

•database performance (indexes, N+1, slow queries)
•caching
•background processing
•changing interpreter, GC
•conditional asset loading, etc
•removing cruft!
Try them first!


This Presentation - Two Parts

• CDN Asset Host using aws*
• unicorn web server*
* Both approaches were tested on heroku, but must work with other hosting solutions


Sample App


NewRelic Monitoring

average load time for mobile traffic only, includes iframed ads


Heroku Dyno Operation


Step 1 - Rack::Cache

Serving assets from rack::cache is faster, and frees up app instance to serve more requests


Static Asset Caching
# Gemfile
gem 'dalli'

# config/application.rb
config.cache_store = :dalli_store

# config/environments/production.rb
config.action_dispatch.rack_cache = {
:metastore => Dalli::Client.new,
:entitystore => 'file:tmp/cache/rack/body',
:allow_reload => false
}
config.serve_static_assets = true
config.assets.digest = true

config.action_controller.perform_caching = true
# provision Memcache addon on Heroku


After Deployment
should see entries like this in your log

cache: [GET /assets/application-c0747cab950350f59304a3815f980622.css] miss, store
cache: [GET /assets/application-032691d4988a7003c42a10995819a0ce.js] miss, store
cache: [GET /assets/s_code.js] miss, store

cache: [GET /assets/application-c0747cab950350f59304a3815f980622.css] fresh
cache: [GET /assets/application-032691d4988a7003c42a10995819a0ce.js] fresh
cache: [GET /assets/s_code.js] fresh


Using Rack::Cache Eﬀect

down from 4.91 / 201 / 2.29 before the change -- not bad for 8 lines of code!


Step 2 - S3 bucket for assets

heroku instance has more time to serve application code because all assets are served from aws s3


S3 Bucket for Assets
# Gemfile
gem "asset_sync" # will push compiled assets into CDN

# Command line
heroku config:add FOG_PROVIDER=AWS
AWS_ACCESS_KEY_ID=xxx
AWS_SECRET_ACCESS_KEY=yyy

heroku config:add FOG_DIRECTORY=yourappname-assets

# config/environments/production.rb
config.action_controller.asset_host =
"//#{ENV['FOG_DIRECTORY']}.s3.amazonaws.com"

# make sure to use AssetTagHelper methods (like image_tag)
# to ensure assets are properly referenced


Now, on git push heroku

assets are automatically synced to s3 anytime ON rake assets:precompile


S3 Bucket eﬀect

down from 4.45 / 179 / 2.43 before the change -- even better!


Step 3 - AWS CloudFront


CloudFront Eﬀect

down from 3.85 / 179 / 2.19 before the change -- Awesome!


Loading Single File
$ time curl http://careersingear.mobi/assets/application-
bdb77a926724ccc3c20b923ab168d89d.js

real 0m0.896s
user 0m0.008s
sys 0m0.016s

----------------

$ time curl http://d3kd72psxbec02.cloudfront.net/assets/
application-bdb77a926724ccc3c20b923ab168d89d.js

real 0m0.293s
user 0m0.006s
sys 0m0.010s

getting a single application.js file from cloud front is 3x faster


WebPageTest ResultsBefore


WebPageTest Results After


Meet Unicorn
• HTTp server for Ruby
• Starts one master process
• forks worker processes
• workers handle requests
• master returns
• one port, several
concurrent requests


Server Setup

Unicorn setup
classic setup
nginx -> unix domain socket -> unicorn
nginx -> smart balancer -> pool of mongrels
workers (os handles load balancing)


Unicorn for Rails App
# Gemfile
gem 'unicorn'

# Procfile
web: bundle exec unicorn -p $PORT -c ./config/unicorn.rb

# config/application.rb
config.logger = Logger.new(STDOUT)

# also, add config/unicorn.rb


Unicorn for Rails App
# config/unicorn.rb
worker_processes 3
timeout 30
preload_app true

before_fork do |server, worker|
if defined?(ActiveRecord::Base)
ActiveRecord::Base.connection.disconnect!
Rails.logger.info('Disconnected from ActiveRecord')
end

if defined?(Resque)
Resque.redis.quit
Rails.logger.info('Disconnected from Redis')
end

end

after_fork do |server, worker|
if defined?(ActiveRecord::Base)
ActiveRecord::Base.establish_connection
Rails.logger.info('Connected to ActiveRecord')
end

if defined?(Resque)
Resque.redis = ENV["REDISTOGO_URL"]
Rails.logger.info('Connected to Redis')
end
end


After Implementing Unicorn

down from 3.64 / 46.7 / 1.17 before the change -- good, but also...


Better Concurrency Handling
require 'typhoeus'
require "benchmark"

URL = "http://careersingear.mobi"
HYDRA = Typhoeus::Hydra.new(max_concurrency: 20)

1000.times do
request = Typhoeus::Request.new(URL, method: :get, timeout: 10000)
request.on_complete do |response|
puts response.code
end
HYDRA.queue(request)
end

Benchmark.bm(7) do |x|
x.report("first:") { HYDRA.run }
end

# using thin
# user system total real
# 1.030000 0.380000 1.410000 ( 16.713791)

# using unicorn
# user system total real
# 1.050000 0.390000 1.440000 ( 7.843766)


And ...

my app can process six concurrent requests on two heroku dynos


Riding Unicorn


To Conclude

• implemented asset cdn
• configured unicorn
• brought down average end user load time from almost
5 sec to 3.5 sec

• app can serve more requests faster and for less $$$


Credits
defunkt, unicorn! https://github.com/blog/517-unicorn
heroku dev center, using rack::cache with memcached in rails 3.1+ https://devcenter.heroku.com/articles/
rack-cache-memcached-rails31
Rice, david, using a cdn asset host with rails 3.1 https://devcenter.heroku.com/articles/cdn-asset-
host-rails31
Sikkes, Michael, Complete Guide to serving your Rails assets over S3 with asset_sync http://blog.firmhouse.com/
complete-guide-to-serving-your-rails-assets-over-s3-with-asset_sync
van roijen, michael, more concurrency on a single heroku dyno with the new celadon cedar stack http://
michaelvanrooijen.com/articles/2011/06/01-more-concurrency-on-a-single-heroku-dyno-
with-the-new-celadon-cedar-stack/


Q&A
This presentation can be found on github github.com/semmin/asset-cdn-and-unicorn-preso
twitter: @status_200
Email: sbagreev@gmail.com

Questions?


Improving Your Heroku App Performance with Asset CDN and Unicorn

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