improving the performance of Rails web Applications

Performance Monitoring
John McCaffrey
1. Why does performance matter?
2. Know your Business Metrics
3. Quick ways assess application performance
4. Monitoring tools to help you track performance

Why does performance matter?
• Revenue
• Costs
• Time
• Competition
• User satisfaction

Why does performance matter?
• Google cares!
• "Speeding up websites is important .. faster sites don't
just improve user experience...improving site speed also
reduces operating costs. Like us, our users place a lot of
value in speed - that's why we've decided to take site
speed into account in our search rankings. "

When should I start caring?
• Capacity planning
• Design
• Growth
• Development
• Testing
• Deployment
• Monitoring

What am I tracking?
Business Metrics

• Page visits per day
• Page visits per user per day
• Time on site
• Searches performed
• Products views
• Orders

SHOPZILLA

Improving
from 6 sec
down to
1.2
seconds

6

Netflix:
43% drop in outbound traffic
after enabling gzip

7

So we know that performance matters.
Now what?

9

Performance Terms
Latency = seconds per job, or "how long it takes"
Throughput = jobs per second, or "how many workers"

Average Response time = average latency
Requests per second = average throughput

If 1 worker that can compute 1 job in .5 sec
latency = .5 secs per job
throughput = 2 jobs per sec

Quick ways to check your stats
• Eyeball the log files
• Use Log reading tool
• Use browser tools
o Confirm your dev env vs staging
• External site tests
o Compare values outside of your network
o Repeatable tests

Eyeball it
Processing UserSessionsController#new (for 127.0.0.1 at
2010-05-15 10:11:09) [GET]
Parameters: {"action"=>"new", "controller"=>"user_sessions"}
Rendering template within layouts/login
Rendering user_sessions/new
Completed in 202ms (View: 105, DB: 42) | 200 OK [http://localhost/
login]

Log analyzer
gem install request-log-analyzer
request-log-analyzer log/development.log

Microsoft tools
– Dynatrace
– MsFast
– VRTA
– Fiddler
– Developer tools

Dom Monster

http://javascriptrocks.com/performance/

18

Are these numbers right?
• Are they consistent?
• Do they seem reasonable
• How can we repeat the tests?
• Can we reproduce them in all environments?
• What should we investigate next?

External tools
– http://zoompf.com
– http://webo.name/
– http://tools.pingdom.com/
– http://gtmetrix.com
– http://www.webpagetest.org/
– http://www.site-perf.com/
– http://webwait.com

Don’t change anything!
– Resist the urge to change a bunch of stuff
– Test coverage
– repeatable perf tests
– don't break anything!
– focus on low hanging fruit first
– get your monitoring in place before you make any
major changes
– don't make it less maintainable
– pair & share

Taking multiple measurements
– Monitor performance over time
– Manually keep an eye on your yslow/resp time
– http://loadimpact.com/
– Apache Bench, Httperf
– Jmeter

showslow.com

http://127.0.0.1/showslow/

Now What?
– Summarize and describe your observations
– Prioritize based on ease of change and expected
impact
– Make your changes in a branch
– Compare your results
– Look for patterns of optimization
– Work with your team

Nuggets of Wisdom
• Gzip
• Get very familiar with yslow
• Look through your logs, analyze them
• Turn on slow query logging for db
• Upgrade your libraries (js, plugins)
• Use RVM (try new plugins, rails, ruby)

30

Upcoming Presentations
– Chicago Javascript
– Improving Page performance

– ChicagoRuby
– Improving Rails app performance
– Improving Developer performance!

– WindyCityRails 2010
– Improving Rails Application Performance

– twitter: @j_mccaffrey

References
– http://railsperformance.blogspot.com/ (me)
– Railslab http://railslab.newrelic.com/
– Steve Souders http://www.stevesouders.com/blog/
– http://velocityconference.blip.tv/
– http://code.google.com/events/io/2010/
– http://speedgeeks-la.blip.tv/
– http://developer.yahoo.com/performance/
– http://code.google.com/speed/page-speed

References
• http://guides.rubyonrails.org/performance_testing.html

33

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