Evolution of GC in CRuby (MRI)

GC is with us from the beginning but it's getting harder and harder to notice with every release. I'm going to talk about shortly the problems of the past implementations and what improvements can we expect in this area.

Transcript

1. Evolution of GC in CRuby (MRI) Balazs Varga Digital Natives
2. (Pre-) 1.8 - Simple Mark & Sweep Source: [5]
3. 1.9.3 - Lazy sweep The issue and the whole discussion is in Japanese… https://bugs.ruby-lang. org/issues/3203 Source: [1]
4. 2.0 - Bitmap Marking GC • The mark phase is rewritten to be non-recursive • Bitmaps for COW safety • COW: Copy On Write
5. 2.0 - Bitmaps for COW safety The Ruby heap contains RValue objects (RString, RHash, parsed code - AST node objects). Source: [2]
6. 2.0 - Bitmaps for COW safety Source: [2]
7. 2.0 - Bitmaps for COW safety Source: [2]
8. 2.0 - Bitmaps for COW safety Source: [1]
9. 2.1 - RGenGC Oldgen and minor marking • generational collector, implemented incrementally • supports C-extensions (backward compatibility) Source: [1]
10. 2.1 - RGenGC Oldgen and minor marking • New options for GC tuning • https://tunemygc.com anyone? Source: [1]
11. 2.1 - RGenGC Oldgen and minor marking Ruby 2.1 ships with new tracepoints that can be used to monitor the GC at runtime. Source: [3]
12. 2.1.1 - “bug” in RGenGC Source: [4] “If ever an objects survives a minor GC it will be flagged as oldgen, these objects will only be scanned during a major GC.” Fixed in 2.1.2, 2.2
13. • Support for symbols • Incremental garbage collection 2.2 - RincGC
14. 2.2 - RincGC Event timing: Source: [5]
15. Future ? SASADA Koichi: Source: [7]
16. [1]: http://tmm1.net/ruby21-rgengc/ [2]: http://patshaughnessy.net/2012/3/23/why-you-should-be-excited-about-garbage-collection-in- ruby-2-0 [3]: http://tmm1.net/ruby21-oobgc/ [4]: http://samsaffron.com/archive/2014/04/08/ruby-2-1-garbage-collection-ready-for-production [5]: https://engineering.heroku.com/blogs/2015-02-04-incremental-gc [6]: http://www.iecc.com/gclist/GC-algorithms.html [7]: http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-core/68630 Resources
17. Contact me http://blog.vbalazs.me https://twitter.com/vbalazs https://github.com/vbalazs balazs.varga@digitalnatives.hu
18. We are hiring! http://jobs.digitalnatives.hu