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GC FAQ
The document discusses the history and features of garbage collection (GC) in Ruby. It notes that while GC has gotten a bad reputation for being slow or causing errors, it has actually been improved over time thanks to contributions from pioneering computer scientists. The document urges readers to see GC as an opportunity to strengthen their skills rather than a scapegoat for performance issues.
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GC FAQ
- 1. GC FAQ nari/Narihiro Nakamura/ @nari_en Network Applied Communication Laboratory Ltd. GC FAQ Powered by Rabbit 0.9.3
- 2. Q: What do you think about REE?
- 3.
- 4. But, REE is basedon Ruby 1.8.7.
- 5. And, Ruby1.9's GChas many cool features.
- 6. Features of Ruby1.9 series ✓ Suppression of Fragmentation - since 1.9.1 ✓ GC::Profiler - since 1.9.1 ✓ LazySweepGC - since 1.9.3 ✓ GC tuning params - since 1.9.3 5/51 GC FAQ Powered by Rabbit 0.9.3
- 7.
- 8. GC tuning params ✓ You can tune GC by using environment variables. ✓ RUBY_GC_MALLOC_LIMIT ✓ RUBY_HEAP_MIN_SLOTS ✓ RUBY_FREE_MIN ✓ Since Ruby 1.9.3 7/51 GC FAQ Powered by Rabbit 0.9.3
- 9. GC tuning params ✓ It's originally and idea from REE. ✓ <URL:http:// www.rubyenterpriseedition.com/ documentation.html#_garbage_collector _performance_tuning> ✓ Please check this page if you are interesting. 8/51 GC FAQ Powered by Rabbit 0.9.3
- 10. BTW, REE adoptsthe Bitmap Marking GC.
- 11. REE's Bitmap Marking ✓ It's implemented on Ruby 1.8's heap structure. ✓ To port it for Ruby 1.9 would be hard. ✓ And, it would be slow. 10/51 GC FAQ Powered by Rabbit 0.9.3
- 12. I want to createa faster Bitmap Marking GC.
- 13. For Ruby 1.9.4or later.
- 14. Q: What do thinkabout the future of CRuby's GC?
- 15. A: We needto break compatibility with CRuby's C extension.
- 16. We need efficientGC algorithms ✓ Generational GC ✓ Incremental GC ✓ Concurrent GC 15/51 GC FAQ Powered by Rabbit 0.9.3
- 17.
- 18. Pains ✓ These algorithms need a write barrier. ✓ We should insert a write barrier on the C extension. ✓ This breaks compatibility of the C extension. 17/51 GC FAQ Powered by Rabbit 0.9.3
- 19. I'll create some toolsfor the transition.
- 20. I'm still thinking about how to do it.
- 21. Q: Why do you like GC?
- 22.
- 23.
- 24. "Beating the Averages" http://www.flickr.com/photos/ringai/2733018174/
- 25.
- 26. "Beaten by the Averages" http://www.flickr.com/photos/ringai/2733018174/
- 27.
- 28.
- 29. e.g. ✓ "Memory isn't freed!" ✓ "The cause is GC!" ✓ "My program is slow!" ✓ "The cause is GC!" 28/51 GC FAQ Powered by Rabbit 0.9.3
- 30. e.g. ✓ "SEGV!!" ✓ "GC!" 29/51 GC FAQ Powered by Rabbit 0.9.3
- 31. GC is always picked on.
- 32.
- 33.
- 34. GC is always picked on :P
- 35. But, GC was madeby really cool hackers.
- 36.
- 37. John McCarthy http://www.flickr.com/photos/null0/272015955/
- 38. He created the Mark& Sweep algorithm on Lisp.
- 39. Marvin L. Minsky taken by Bcjordan : http://en.wikipedia.org/wiki/File:Marvin_Minsky_at_OLPCb.jpg
- 40. He created the Copying GC algorithm.
- 41. Edsger Wybe Dijkstra photo 息2002 Hamilton Richards : http://userweb.cs.utexas.edu/users/EWD/
- 42.
- 43. Donald Ervin Knuth Flickr user Jacob Appelbaum : http://flickr.com/photos/ioerror/56359970/in/set-1220741/
- 44. He created Lisp2(oneof Mark Compact algorithms).
- 45. And many other hackers havestudied GC.
- 46. That means GC is the training school of Hackers!
- 47.
- 48. Become stronger bybeing beaten!
- 49. Let's become stronger bybeing beat together with GC.
- 50.
- 51.
- 52. Let's train in GC since now!!