![RVALUE
GC::INTERNAL_CONSTANTS[:RVALUE_SIZE]
# => 40
* sizeof(RVALUE) is
* 20 if 32-bit, double is 4-byte aligned
* 24 if 32-bit, double is 8-byte aligned
* 40 if 64-bit](https://image.slidesharecdn.com/gc-160127223355/85/mri-ruby-GC-14-320.jpg)
![heap_page
GC::INTERNAL_CONSTANTS[:HEAP_OBJ_LIMIT]
# => 408
HEAP_PAGE_OBJ_LIMIT =
((HEAP_PAGE_SIZE - sizeof(struct heap_page_header)) /
sizeof(struct RVALUE))](https://image.slidesharecdn.com/gc-160127223355/85/mri-ruby-GC-15-320.jpg)
![RString
struct RString {
struct RBasic basic;
union {
struct {
long len;
char *ptr;
union {
long capa;
VALUE shared;
} aux;
} heap;
char ary[RSTRING_EMBED_LEN_MAX + 1];
} as;
};](https://image.slidesharecdn.com/gc-160127223355/85/mri-ruby-GC-17-320.jpg)
![Mark & Sweep
ObjectSpace.reachable_objects_from_root.keys
[
[0] "vm",
[1] "machine_context",
[2] "global_list",
[3] "end_proc",
[4] "global_tbl"
]](https://image.slidesharecdn.com/gc-160127223355/85/mri-ruby-GC-21-320.jpg)
![heap_page
struct heap_page {
struct heap_page *prev;
short total_slots;
short free_slots;
short final_slots;
struct heap_page *free_next;
struct heap_page *next;
/* the following three bitmaps are cleared at the beginning of full GC */
bits_t mark_bits[HEAP_PAGE_BITMAP_LIMIT];
};](https://image.slidesharecdn.com/gc-160127223355/85/mri-ruby-GC-36-320.jpg)
mri ruby GC
- 2. Аудитория
- 6. heap_page_free(rb_objspace_t *objspace, struct heap_page *page) { free(page); }
- 7. О чем поговорим • как работает GC • как устроен GC • планы ruby team
- 8. gc.c 9381 lines and counting
- 10. Через пару дней
- 11. Чем занимается • создает объекты • выделяет память под них • освобождает • собирает статистику • проверяет консистентность объектов • … • собирает мусор
- 12. Структура
- 14. RVALUE GC::INTERNAL_CONSTANTS[:RVALUE_SIZE] # => 40 * sizeof(RVALUE) is * 20 if 32-bit, double is 4-byte aligned * 24 if 32-bit, double is 8-byte aligned * 40 if 64-bit
- 15. heap_page GC::INTERNAL_CONSTANTS[:HEAP_OBJ_LIMIT] # => 408 HEAP_PAGE_OBJ_LIMIT = ((HEAP_PAGE_SIZE - sizeof(struct heap_page_header)) / sizeof(struct RVALUE))
- 16. RVALUE typedef struct RVALUE { union { struct { VALUE flags; /* always 0 for freed obj */ struct RVALUE *next; } free; struct RBasic basic; struct RObject object; struct RClass klass; struct RString string; ... struct RComplex complex; ... } as; } RVALUE;
- 17. RString struct RString { struct RBasic basic; union { struct { long len; char *ptr; union { long capa; VALUE shared; } aux; } heap; char ary[RSTRING_EMBED_LEN_MAX + 1]; } as; };
- 18. Развитие • early - Mark & Sweep • 1.9.3 - Lazy Sweep • 2.0 - CoW friendly • 2.1 - Mark major / minor • 2.2 - Inc major Mark, symbols
- 19. Mark & Sweep
- 20. Mark & Sweep
- 21. Mark & Sweep ObjectSpace.reachable_objects_from_root.keys [ [0] "vm", [1] "machine_context", [2] "global_list", [3] "end_proc", [4] "global_tbl" ]
- 22. Mark & Sweep
- 23. Mark & Sweep
- 24. Mark & Sweep > a = 'a' * 1024 * 1024 * 500 > a = nil; 4.times { GC.start }
- 25. Mark & Sweep
- 26. Mark gc_mark_roots(rb_objspace_t *objspace, const char **categoryp) { rb_thread_t *th = GET_THREAD(); rb_vm_mark(th->vm); mark_tbl(objspace, finalizer_table); mark_current_machine_context(objspace, th); rb_gc_mark_encodings(); /* mark protected global variables */ rb_gc_mark_maybe(*list->varptr); rb_mark_end_proc(); rb_gc_mark_global_tbl(); }
- 27. Sweep gc_sweep(rb_objspace_t *objspace) { if (immediate_sweep) { gc_sweep_start(objspace); gc_sweep_rest(objspace); } else { } gc_heap_prepare_minimum_pages(objspace, heap_eden); }
- 29. Sweep gc_sweep_step(rb_objspace_t *objspace, rb_heap_t *heap) { while (sweep_page) { heap->sweep_pages = next = sweep_page->next; gc_page_sweep(objspace, heap, sweep_page); heap_unlink_page(objspace, heap, sweep_page); heap_add_page(objspace, heap_tomb, sweep_page); sweep_page = next; } if (heap->sweep_pages == NULL) { gc_sweep_finish(objspace); } return heap->free_pages != NULL; }
- 32. Lazy Sweep
- 33. Lazy Sweep gc_sweep_continue(rb_objspace_t *objspace, rb_heap_t *heap)
- 36. heap_page struct heap_page { struct heap_page *prev; short total_slots; short free_slots; short final_slots; struct heap_page *free_next; struct heap_page *next; /* the following three bitmaps are cleared at the beginning of full GC */ bits_t mark_bits[HEAP_PAGE_BITMAP_LIMIT]; };
- 37. RGenGC
- 38. Major
- 39. Minor
- 40. Minor
- 41. Minor
- 42. 4.times { GC.start }
- 43. if (objspace->last_major_gc > 3 /* magic number */) { gc_report(1, objspace, "gc_marks_finish: next is full GC!!)n"); objspace->rgengc.need_major_gc |= GPR_FLAG_MAJOR_BY_NOFREE; } Major через каждые 3 Minor цикла
- 44. RIncGC только для Major Mark
- 46. RIncGC Major Mark objspace->rincgc.step_slots = (objspace->marked_slots * 2) / ((objspace->rincgc.pooled_slots / HEAP_PAGE_OBJ_LIMIT) + 1);
- 48. RIncGC Major Mark heap_prepare(rb_objspace_t *objspace, rb_heap_t *heap)
- 49. RGenGC RIncGC
- 50. Restricted
- 51. Много слайдов про remember set
- 52. Много слайдов про write unprotected objects
- 53. Немного слайдов про write protected objects
- 54. Можно найти • http://www.atdot.net/~ko1/activities/ 2015_rubyconfph_pub.pdf • http://www.atdot.net/fp_store/f.p61can/file.data- incremental-gc.pdf
- 55. Дополнительно • http://tmm1.net/ruby21-rgengc/ • https://ruby-hacking-guide.github.io/gc.html • Ruby Under a Microscope - Pat Shaughnessy • http://engineering.heroku.com/blogs/2015-02-04- incremental-gc