[ruby-core:122328] [Ruby Bug#21368] Moving objects with finalizer between Ractors crashes

Issue #21368 has been updated by osyoyu (Daisuke Aritomo).

File 0001-Bug-21368-Transfer-finalizer-when-moving-between-Rac.patch added

The script in the description didn't crash in my environments (the following). Explicitly calling `GC.start` did.

- Linux `ruby 3.5.0dev (2025-05-28T04:34:40Z master d064fd067b) +PRISM [x86_64-linux]` 
- macOS `ruby 3.5.0dev (2025-05-28T04:34:40Z master d064fd067b) +PRISM [arm64-darwin24]`

```ruby
r = Ractor.new do
  Ractor.receive # don't bind to a variable (let it be garbage collected)
  GC.start
end

o = Object.new
ObjectSpace.define_finalizer(o, proc { |id| })
r.send(o, move: true)

r.take
```

I have attached an updated version of @zzak_'s patch which resolves this crash, but I suppose this is inappropiate since this will leak outer variables in the following case:

```ruby
r = Ractor.new do
  Ractor.receive
  GC.start # `unshareable` happens to get read in this Ractor
end

o = Object.new
unshareable = +"hello"
ObjectSpace.define_finalizer(o, proc { |id| p unshareable })
r.send(o, move: true)

r.take
```

Maybe simply marking objects with a finalizer ineligible for moving is more appropiate.

----------------------------------------
Bug #21368: Moving objects with finalizer between Ractors crashes
https://bugs.ruby-lang.org/issues/21368#change-113475

* Author: peterzhu2118 (Peter Zhu)
* Status: Assigned
* Assignee: ractor
* Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN
----------------------------------------
When an object is moved to a different Ractor, the finalizers are not copied to the new object, so it will have the `FL_FINALIZE` flag set but no entry in the finalizer table.

The following script crashes:

```ruby
r = Ractor.new do
  loop { Ractor.receive }
end

1_000.times do
  o = Object.new
  ObjectSpace.define_finalizer(o, proc { |id| })
  r.send(o, move: true)
end
```

---Files--------------------------------
0001-Bug-21368-Transfer-finalizer-when-moving-between-Rac.patch (883 Bytes)


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