This is another approach to solve an issue discussed at r43530.
This feature is diabled as default.
This feature measures an increment of memory consuption by oldgen
objects. It measures memory consumption for each objects when
the object is promoted. However, measurement of memory consumption
is not accurate now. So that this measurement is `estimation'.
To implement this feature, move memsize_of() function from
ext/objspace/objspace.c and expose rb_obj_memsize_of().
Some memsize() functions for T_DATA (T_TYPEDDATA) have problem to
measure memory size, so that we ignores T_DATA objects now.
For example, some functions skip NULL check for pointer.
The macro RGENGC_ESTIMATE_OLDSPACE enables/disables this feature,
and turned off as default.
We need to compare 3gen GC and this feature carefully.
(it is possible to enable both feature)
We need a help to compare them.
* internal.h: expose rb_obj_memsize_of().
* ext/objspace/objspace.c: use rb_obj_memsize_of() function.
* cont.c (fiber_memsize): fix to check NULL.
* variable.c (autoload_memsize): ditto.
* vm.c (vm_memsize): ditto.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43532 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
RGenGC is designed as 2 generational GC, young and old generation.
Young objects will be promoted to old objects after one GC.
Old objects are not collect until major (full) GC.
The issue of this approach is some objects can promoted as old
objects accidentally and not freed until major GC.
Major GC is not frequently so short-lived but accidentally becoming
old objects are not freed.
For example, the program "loop{Array.new(1_000_000)}" consumes huge
memories because short lived objects (an array which has 1M
elements) are promoted while GC and they are not freed before major
GC.
To solve this problem, generational GC with more generations
technique is known. This patch implements three generations gen GC.
At first, newly created objects are "Infant" objects.
After surviving one GC, "Infant" objects are promoted to "Young"
objects.
"Young" objects are promoted to "Old" objects after surviving
next GC.
"Infant" and "Young" objects are collected if it is not marked
while minor GC. So that this technique solves this problem.
Representation of generations:
* Infant: !FL_PROMOTED and !oldgen_bitmap [00]
* Young : FL_PROMOTED and !oldgen_bitmap [10]
* Old : FL_PROMOTED and oldgen_bitmap [11]
The macro "RGENGC_THREEGEN" enables/disables this feature, and
turned off as default because there are several problems.
(1) Failed sometimes (Heisenbugs).
(2) Performance down.
Especially on write barriers. We need to detect Young or Old
object by oldgen_bitmap. It is slower than checking flags.
To evaluate this feature on more applications, I commit this patch.
Reports are very welcome.
This patch includes some refactoring (renaming names, etc).
* include/ruby/ruby.h: catch up 3gen GC.
* .gdbinit: fix to show a prompt "[PROMOTED]" for promoted objects.
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This flag represents that "this object is promoted at least once."
* gc.c, debug.c, object.c: catch up this change.
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* gc.c (obj_free): suppress a false shorten-64-to-32 warning,
RUBY_TYPED_FREE_IMMEDIATELY never exceed the limit of int.
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performance. Add before_sweep condition to heap_page structure.
* gc.c (rb_gc_force_recycle): Use before_sweep member.
* gc.c (heap_is_before_sweep, is_before_sweep): Remove. They has not
already been used.
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* gc.c (is_live_object): finalizer may not run because of lazy-sweep.
[ruby-dev:47786] [Bug #9069]
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* RUBY_TYPED_FREE_IMMEDIATELY: free the data given by DATA_PTR()
with dfree function immediately. Otherwise (default), the data
freed at finalizaton point.
* RUBY_TYPED_WB_PROTECTED: make this object with FL_WB_PROTECT
(not shady).
* gc.c (obj_free): support RUBY_TYPED_FREE_IMMEDIATELY.
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We only need one sweep time measurement without lazy sweep.
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* gc.c (GC_MALLOC_LIMIT): change default value to 16MB.
* gc.c (GC_MALLOC_LIMIT_GROWTH_FACTOR): change default value to 2.0.
* gc.c (gc_before_sweep): change decrease ratio of `malloc_limit'
from 1/4 to 1/10.
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gc_rest_sweep() can reduce malloc_increase, so try it before GC.
Otherwise, malloc_increase can be less than malloc_limit at
gc_before_sweep(). This means that re-calculation of malloc_limit
may be wrong value.
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After rb_gc_force_recycle() for a object blonging to heap->freelist,
`heap->using_page->freelist' is not null.
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Share `increment' information with heaps.
* gc.c: change ratio of heap_pages_free_min_page
to 0.80.
This change means slow down page freeing speed.
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Tomb heap is where zombie objects and ghost (freed slot) lived in.
Separate from other heaps (now there is only eden heap) at sweeping
helps freeing pages more efficiently.
Before this patch, even if there is an empty page at former phase
of sweeping, we can't free it.
Algorithm:
(1) Sweeping all pages in a heap and move empty pages from the
heap to tomb_heap.
(2) Check all exsisting pages and free a page
if all slots of this page are empty and
there is enough empty slots (checking by swept_num)
To introduce this pach, there are several tuning of GC parameters.
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Now, objects are managed by page. And a set of pages is called heap.
This commit supports multiple heaps in the object space.
* Functions heap_* and rb_heap_t manages heap data structure.
* Functions heap_page_* and struct heap_page manage page data
strcuture.
* Functions heap_pagse_* and struct rb_objspace_t::heap_pages
maintains all pages.
For example, pagaes are allocated from the heap_pages.
See https://bugs.ruby-lang.org/projects/ruby-trunk/wiki/GC_design
and https://bugs.ruby-lang.org/attachments/4015/data-heap_structure_with_multiple_heaps.png
for more deitals.
Now, there is only one heap called `eden', which is a space for all
new generated objects.
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There is a bug that T_ZOMBIE objects are not collected.
Because there is a pass to miss finalizer postponed job
with multi-threading. This patch solve this issue.
* vm_trace.c (rb_postponed_job_register_one): set
RUBY_VM_SET_POSTPONED_JOB_INTERRUPT(th) if another same job
is registered.
There is a possibility to remain a postponed job without
interrupt flag.
* vm_trace.c (rb_postponed_job_register_one): check interrupt
carefully.
* vm_trace.c (rb_postponed_job_register_one): use additional space
to avoid buffer full.
* gc.c (gc_finalize_deferred_register): check failure.
* thread.c (rb_threadptr_execute_interrupts): check
`postponed_job_interrupt' immediately. There is a possibility
to miss this flag.
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* make "struct heap" and move most of variables
in rb_objspace_t::heap.
* rename rb_objspace_t::heap::sorted to
rb_objspace_t::heap_sorted_pages
and make a macro heap_sorted_pages.
* rename rb_objspace_t::heap::range to
rb_objspace_t::heap_range and rename macros
lomem/himem to heap_lomem/heap_himem.
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Change "slot" to "page". "Slot" is a space of RVALUE.
1. "Heap" consists of a set of "heap_page"s (pages).
2. Each "heap_page" has "heap_page_body".
3. "heap_page_body" has RVALUE (a.k.a. "slot") spaces.
4. "sorted" is a sorted array of "heap_page"s, sorted
by address of heap_page_body (for "is_pointer_to_heap").
See https://bugs.ruby-lang.org/attachments/4008/data-heap_structure.png.
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This macro enable checker compare with allocated memory and
declared old_size of sized_xfree and sized_xrealloc.
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This API provides information which objects are root objects.
`category' shows what kind of root objects.
* gc.c (gc_mark_roots): separate from gc_marks_body().
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* vm.c, vm_core.h (rb_vm_add_root_module): added to register as a
defined root module or class.
This guard helps mark miss from defined classes/modules they are
only refered from C's global variables in C-exts.
Basically, it is extension's bug.
Register to hash object VM has.
Marking a hash objects allows generational GC supports.
* gc.c (RGENGC_PRINT_TICK): disable (revert).
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