Caching with Ruby

1. Caching with Ruby
Hoa.N + Luong.V

2. Outline
1. What is cache/caching
2. Caching with Ruby/Rails (Framework and
Language level)

3. What is cache/caching
1. Cache ? Why ?
2. The good the bad the ugly
3. Different levels of cache

4. Why do we cache?
But what is a cache?

5. Cache/Caching
In computing, a cache is a hardware or software component
that stores data so that future requests for that data can
be served faster; the data stored in a cache might be the
result of an earlier computation or a copy of data stored
elsewhere
// Wikipedia

6. Cache/Caching
Precompute and serve content superfast
// Luong

7. Why do we cache precompute and serve content superfast?
- Improve Application Performance
- Reduce database cost
- Reduce load on backend
- Predictable performance
- Eliminate Database Hotspots
- Increase Read Throughput

8. Facebook TAO model - https://www.facebook.com/notes/facebook-engineering/tao-the-power-of-the-graph/10151525983993920/

9. Twitter timeline - https://www.infoq.com/presentations/Twitter-Timeline-Scalability

10. Reddit

11. The good the bad the ugly
https://github.com/reddit-archive/reddit/blob/master/r2/r2/lib/db/queries.py

12. Caching is hard
There are only two hard things in Computer Science: cache invalidation and naming things.
-- Phil Karlton
- Cache invalidation
- Code complexity
- More resources to manage
- Hard to fix data related bugs
- ....

13. Different levels of cache

14. Application Caching

15. CDN caching

16. Browser caching

17. CDN caching

18. Caching with Ruby/Rails
1. Outdated caching mechanism
2. Memoization
3. Thread-safe in-memory with Ruby/Rails
4. Low-level caching
5. SQL caching

19. OUTDATED CACHING MECHANISM

20. 1. PAGE CACHING
2. ACTION CACHING
3. RUSSIAN CACHING
OUTDATED CACHING MECHANISM

21. Memoization

22. Memoization
https://github.com/Thinkei/eh-monitoring/blob/master/lib/eh_monitoring

23. https://api.rubyonrails.org/v3.1/classes/ActiveSupport/Memoizable.html

24. Thread-safe in-memory with Ruby/Rails

26. Using the current thread to
cache the value you want

27. And this is how this mechanism has been applied in Rails
https://github.com/rails/rails/blob/b9ca94caea2ca6a6cc09abaffaad67b447134079/activesupport/lib/active_support/core_ext/
module/attribute_accessors_per_thread.rb#L145

28. LOW LEVEL CACHING

29. LOW LEVEL CACHING

30. LOW LEVEL CACHING

31. SQL LEVEL CACHING

32. SQL LEVEL CACHING

33. Q & A

34. THANK YOU