Rails Performance Tricks and Treats

Rails Performance Tricks and Treats Marshall Yount Yount Labs

Everything I really need to know about code optimization I learned by playing Quake

The Big Picture • What is Performance? • How do we know we’re performant? • What tools do we use? • How do we ﬁx problems? • Demonstration

Different ways of looking at performance • Client perceived • Server

Client • slow loading web page (latency) • slow executing webpage (javascript/css) http://www.ﬂickr.com/photos/7423510@N06/2984486385/

The Enemy Latency: It’s a bitch

The Enemy http://www.ﬂickr.com/photos/peterhaza/3492771467/ Latency: It’s a bitch

Diagnostic Tools (Client) • Firebug • YSlow • PageSpeed • UserTime

Reducing Roundtrips • CSS Sprites • CSS Data URIs • Jammit • Rails *_link_tag http://www.ﬂickr.com/photos/mezzoblue/3217540317/

Reducing Roundtrips • CSS Sprites ul.checklist li.complete { margin-left: 20px; background: • CSS Data URIs url('data:image/ png;base64,AAAAFGGFyjOXZtQAAAAAElFT...') • Jammit top left no-repeat; } • Rails *_link_tag

Reducing Roundtrips <%= stylesheet_link_tag "main", "nav", • CSS Sprites "blog", :cache => “pagename_all” %> • CSS Data URIs <link href="/stylesheets/ • Jammit pagename_all.css?1234567890" media="screen" rel="stylesheet" • Rails *_link_tag type="text/css" />

HTTP Hacking for Fun and Proﬁt • Off with her <HEAD> • Expires: • Last-Modiﬁed: • ETag: • Content-Encoding:

Server • registers • memory • network • database • disk • APIs http://www.ﬂickr.com/photos/buro9/298998011/

Infrastructure • squid 2.7 • varnish • memcached • redis / resque

Top Clones • top • htop • mytop • memcache-top

Monitoring -- free • nagios • cacti • zabbix • zenoss (core)

Monitoring -- paid • Pingdom Text • NewRelic • Scout

Monitoring -- paid • Pingdom • NewRelic • Scout

Fixing Problems • Performance is a moving target! • Horizontal/ Vertical scaling http://www.ﬂickr.com/photos/tpapi/2765541278/

NewRelic Workﬂow • Web Transactions • Most Time Consuming • Slowest Average Response Time • Database

And the Number One Ruby on Rails Performance Problem Is ...

And the Number One Ruby on Rails Performance Problem Is ... N+1 Select

N+1 Select photos.each do |photo| puts photo.rating.id puts photo.user.email puts photo.camera.name end How many queries does this execute?

N+1 Select photos = Photo.ﬁnd(:all, :include => [:rating, :user, :email]) photos.each do |photo| puts photo.rating.id puts photo.user.email puts photo.camera.name end How many queries does this execute?

Plugins/Gems • bullet • slim_scrooge • query_reviewer • ambitious_query_indexer • ActiveRecord::Extensions

Still not fast enough for ya? • ruby-prof • memprof - where are objects being created • change interpreters • ree -- gc.enable stats • jruby • ruby 1.9

Readings • Mark Nottingham’s HTTP caching tutorial • http://www.mnot.net/cache_docs/ • YSlow Best Practices • http://developer.yahoo.com/performance/rules.html • http://delicious.com/marshall.yount/performance

Tools • http://documentcloud.github.com/jammit/ • http://jeremy.zawodny.com/mysql/mytop/ • http://htop.sourceforge.net/ • http://code.google.com/p/memcache-top/

Appendix • The following incomplete slides were suggested by audience members at the Dallas Ruby Brigade. I’ll be ﬂeshing these out and adding them to a future version of the presentation.

Rails caching model

Template rendering pain

Database Model Fields • wasteful data types • varchars •

Evented API calls

Rails Performance Tricks and Treats

by Marshall Yount on Aug 10, 2010

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