In cb1ea54bbf I added one more
metadata flag, but didn't notice `RB_GC_OBJECT_METADATA_ENTRY_COUNT`
had to be incremented.
This should fix ASAN builds.
Interestingly, bdb25959fb already
caused the count to be off by one, so I had to increment it by
2.
Given that the currently planned ractor local GC implementation
performance will heavilly be influenced by the number of shareable
objects it would be valuable to be able to know how many of them
are in the heap.
`objspace->finalizer_table` must be synchronized,
otherwise concurrent insertion from multiple ractors
will cause a crash.
Repro:
```ruby
ractors = 5.times.map do |i|
Ractor.new do
100_000.times.map do
o = Object.new
ObjectSpace.define_finalizer(o, ->(id) {})
o
end
end
end
ractors.each(&:take)
```
This inverse table is only useful if `ObjectSpace._id2ref` is used,
which is extremely rare. The only notable exception is the `drb` gem
and even then it has an option not to rely on `_id2ref`.
So if we assume this table will never be looked up, we can just
not maintain it, and if it turns out `_id2ref` is called, we
can lock the VM and re-build it.
```
compare-ruby: ruby 3.5.0dev (2025-04-10T09:44:40Z master 684cfa42d7) +YJIT +PRISM [arm64-darwin24]
built-ruby: ruby 3.5.0dev (2025-04-10T10:13:43Z lazy-id-to-obj d3aa9626cc) +YJIT +PRISM [arm64-darwin24]
warming up..
| |compare-ruby|built-ruby|
|:----------|-----------:|---------:|
|baseline | 26.364M| 25.974M|
| | 1.01x| -|
|object_id | 10.293M| 14.202M|
| | -| 1.38x|
```
[Bug #21214]
If we allocate objects where one heap holds transient objects and another
holds long lived objects, then the heap with transient objects will grow
along the heap with long lived objects, causing higher memory usage.
For example, we can see this issue in this script:
def allocate_small_object = []
def allocate_large_object = Array.new(10)
arys = Array.new(1_000_000) do
# Allocate 10 small transient objects
10.times { allocate_small_object }
# Allocate 1 large object that is persistent
allocate_large_object
end
pp GC.stat
pp GC.stat_heap
Before this change:
heap_live_slots: 2837243
{0 =>
{slot_size: 40,
heap_eden_pages: 1123,
heap_eden_slots: 1838807},
2 =>
{slot_size: 160,
heap_eden_pages: 2449,
heap_eden_slots: 1001149},
}
After this change:
heap_live_slots: 1094474
{0 =>
{slot_size: 40,
heap_eden_pages: 58,
heap_eden_slots: 94973},
2 =>
{slot_size: 160,
heap_eden_pages: 2449,
heap_eden_slots: 1001149},
}
[Bug #20271]
[Bug #20267]
[Bug #20255]
`rb_obj_alloc(RBASIC_CLASS(obj))` will always allocate from the basic
40B pool, so if `obj` is larger than `40B`, we'll create a corrupted
object when we later copy the shape_id.
Instead we can use the same logic than ractor copy, which is
to use `rb_obj_clone`, and later ask the GC to free the original
object.
We then must turn it into a `T_OBJECT`, because otherwise
just changing its class to `RactorMoved` leaves a lot of
ways to keep using the object, e.g.:
```
a = [1, 2, 3]
Ractor.new{}.send(a, move: true)
[].concat(a) # Should raise, but wasn't.
```
If it turns out that `rb_obj_clone` isn't performant enough
for some uses, we can always have carefully crafted specialized
paths for the types that would benefit from it.
Was reading some assembly and noticed the dead branches generated for
FL_TEST(). Just a quick basic pass to change the obvious places; there
may be other opportunities.
Moving object_id dumping from ObjectSpace to the GC flags allows ObjectSpace
to not assume the FL_SEEN_OBJ_ID flag and instead move it to the responsibility
of the GC.
This function replaces the internal rb_obj_gc_flags API. rb_gc_object_metadata
returns an array of name and value pairs, with the last element having
0 for the name.
we had been using a stub weak definition of `mprotect` in wasm/missing.c
so far, but wasi-sdk 23 added mprotect emulation to wasi-libc[^1], so the
emulation is now linked instead. However, the emulation doesn't support
PROT_NONE and fails with ENOSYS, so we need to avoid calling mprotect
completely on WASI.
[^1]: 7528b13170
For moving garbage collectors, we may want to combine liveliness checking
with reference updating for performance. This commit allows for non-weak
references to be passed into the callback function when weak_only is false.
Previously, generic ivars worked differently than the other global tables
during compaction. The other global tables had their references updated
through iteration during rb_gc_update_vm_references. Generic ivars updated
the keys when the object moved and updated the values while reference
updating the object. This is inefficient as this required one lookup for
every moved object and one lookup for every object with generic ivars.
Instead, this commit changes it to iterate over the generic ivar table to
update both the keys and values.
- Split static recipes to depend file.
- Modify makefile configurations in the block to `create_makefile`.
- Expand rust sources in extconf.rb instead of GNU make extension.
TODO: pass `CARGO_TARGET_DIR` without shell syntax.
