The document discusses various memory issues that can occur in Ruby and Rails applications, including bloat, memory leaks, and memory churn. It provides examples of each issue and recommends using the Oink gem to monitor memory usage and identify problems. The document also advises stopping the use of global state, limiting object mutation to reduce memory churn, and exploring object graphs to find memory leaks. Best practices are presented for configuring memory monitoring and troubleshooting performance issues.

1. Visual representations of
memory issues in Ruby
and Rails
Camille Baldock, @camille_

4. Bloat
• Memory usage has grown with data set
• Loading too many objects at once

5. Memory leaks
• Objects that will never be released by the
garbage collector
• Objects whose size grows the longer the
process runs

6. Memory churn
• Allocating and deallocating a LOT of objects

7. • Oink
• Ruby object graphs
• A few best practices…
!

8. Configuring Oink
• Rails.application.middleware.use( Oink::Middlew
are, :instruments => :memory )
!
• Rails.application.middleware.use( Oink::Middlew
are, :instruments => :activerecord )

9. !
• ReportsController#show
• Max heap size: 157524 KB
• Number of AR objects: 14565

10. Be proactive
about
being lazy

11. Where are the leaks ?
• Look at the object graph in memory !
• ObjectSpace.find_references
• A new ObjectGraph standard library

12. Journey through the object
graph

13. Counting objects…

14. Finding something horrible…

15. !
• status?timestamp=110143244
• status?timestamp=110143245
• ….

16. Stop using global state !
• Global variables
• Class variables
• Per-process instance state
• …

17. My app is still slow…

18. Sources of memory churn

19. Mutation limits allocation

20. • Twitter: @camille_
• Github: camilleldn
!
• Conrad Irwin, Object Graph exploration for Ruby
memory leaks
• Oink gem, https://github.com/noahd1/oink
• Boston Ruby - Joe Ferris - Memory Issues in Rails