This was a lightning talk presented at Women Who Code Sydney May 2014. A look into some techniques that can be applied to RoR apps (and most apps in general) on how to improve performance. We'll be looking into scaling, caching and other methods to grow from a single server database app to bigger apps :)

1. Performance for RoR Apps
(some tips)

2. About Me
clairettran

3. Performance Is Important
Yay!
● AirBnb, Netflix, Twitter*, Facebook, Zynga
* Used to have outages, but fixed their performance issues
● Jetstar ticket sales
Oops!
● Myer Boxing Day 2013
● Click Frenzy 2012

4. Example Stats for SMH
At Peak: 28K requests per minute
14th May: 4,000,000 hits to the site

5. Some Common Problems
● Memory leaks
● Long running API call(s)
● Slow synchronous processes
(e.g. Emails, PayPal)
● Slow database queries
● Network issues
Note: not an exhaustive list

6. What I’ll Cover
● Monitoring
● Caching
● Scaling
● Database

7. Monitoring
How to know there is a performance problem?
+ Response time, rpm, memory usage, CPU usage, error
rates

8. Monitoring
What else can I do?
● Logs (e.g. file server, splunk, loggly, logstash)
● Memory Usage (e.g. unix top command)
● Performance tests (e.g. Apache bench, JMeter, Neoloader)
● Health Checks (e.g. health_check gem, Nagios, Sitescope)
● More calls to the call centre

9. Caching
How?
● Cache store (key-value store)
● Fragment caching (part of
the page)
● SQL caching (cache query
results)
Removed in Rails4: Action Caching & Fragment Caching

10. Caching
Before: No Caching
After: With Caching!
Problem: Page making long running/many external requests

11. Scaling
Load Balancer
www.mysite.com
Cache Cluster
Cache
Static
Files
(css, js,
images)
Virtual IP
Replication(Active-Passive)

12. Database
● Add an index
● Profiling
● Batch queries
● Eager fetching
● Denormalisation
● Sharding

13. Other Techniques
● Queuing/Background Jobs
● Caching
● Dedicated services
● Rails engines
● C-extensions (gems)
● Sprites
● Asset pipeline
● Cache control headers
● Gzip assets
● Less HTTP requests
● Dedicated Search Service
● Remove unused assets (are all
those bootstrap files needed?)
● Static cluster
● AWS Auto-scaling
● Akamai (edge caching)
● YSlow
● Local Storage
● Smaller Responses
● Async JS
● Chrome DevTools
● JRuby

14. Further Reading
https://github.com/ianheggie/health_check
http://guides.rubyonrails.org/caching_with_rails.html
http://railscasts.com/episodes/380-memcached-dalli
https://developers.google.com/events/io/sessions/324511365
http://railscasts.com/episodes/366-sidekiq
http://www.slideshare.net/derekmbrown/netflix-strategic-performance-
analysis
http://blog.jphpsf.com/2012/04/28/front-end-performance-case-study-github

16. Questions