Optimizing Ruby's Memory Layout

on YouTube ↗27m

" summary

Proposal moves malloced object payloads into the ruby heap by allocating variable-size slots (power-of-two multiples of the 40‑byte rvalue) and per‑size size pools, placing payload immediately after the rvalue to improve cache locality. Implementation covers classes and strings, handles resizing by falling back to malloc today, and leans on compaction as a future fix. Microbenchmarks show 35% faster string compare and other ops faster; production testing across ~500M requests yields 4% memory reduction with no latency impact on 71‑byte strings.

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" chapters (28)

1. 0:00Intro
2. 0:48RVALUE structure
3. 1:14Ruby Object Structure
4. 1:40Heap page structure
5. 2:43Allocating Ruby objects
6. 3:45Ruby's garbage collector
7. 4:16Marking phase
8. 4:35Marking example
9. 5:44Sweeping example
10. 6:20Compact phase
11. 6:50Compaction algorithm
12. 7:08Compaction example
13. 9:05Allocating an embedded string
14. 10:57CPU cache properties
15. 11:54Ruby cache performance
16. 12:31Overhead of malloc
17. 13:12The Variable Width Allocation project
18. 13:48Variable Width cache performance
19. 15:21RClass Allocation
20. 17:33Size pools
21. 18:55Types of String allocation
22. 19:23Allocating a short string
23. 20:13Allocating a longer string
24. 20:46Resizing a string
25. 23:01railsbench
26. 23:33rdoc generation
27. 25:32Resizing objects
28. 26:07Shrinking RVALUE

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