[ruby-core:121945] [Ruby Bug#21315] Finalizers violate the `rb_ractor_confirm_belonging` assertion

Issue #21315 has been updated by Eregon (Benoit Daloze).


When a Ractor terminates just before it actually does so it should probably run the remaining finalizers, AFAIK, this is what CRuby does when the process is about to terminate and there are finalizers not run yet (but I might be wrong, though it clearly seems to exhibit that behavior).

3 is a no-no, it's already quite difficult to write correct finalizers (which don't capture the object to finalize), it's basically impossible to write them as shareable procs.

----------------------------------------
Bug #21315: Finalizers violate the `rb_ractor_confirm_belonging` assertion
https://bugs.ruby-lang.org/issues/21315#change-113065

* Author: byroot (Jean Boussier)
* Status: Open
* Assignee: ractor
* Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN
----------------------------------------
Reproduction (with assertions enabled):

```ruby
require "tempfile"

Ractor.new do
  10.times do
    Tempfile.new
  end
end.take

GC.start
```

```
  <OBJ_INFO:rb_ractor_confirm_belonging@../src/ractor_core.h:375> (File)
  /home/runner/work/ruby/ruby/src/lib/tempfile.rb:387: [BUG] rb_ractor_confirm_belonging object-ractor id:1, current-ractor id:2
  ruby 3.5.0dev (2025-05-09T15:51:24Z pull/13291/merge e289a1dc58) +PRISM [x86_64-linux]
  
  -- Control frame information -----------------------------------------------
  c:0005 p:0007 s:0025 e:000024 METHOD /home/runner/work/ruby/ruby/src/lib/tempfile.rb:387 [FINISH]
  c:0004 p:0022 s:0020 e:000019 METHOD /home/runner/work/ruby/ruby/src/lib/prism/parse_result.rb:833 [FINISH]
  c:0003 p:---- s:0012 e:000011 CFUNC  :parse_lex_file
  c:0002 p:0006 s:0007 e:000006 BLOCK  /home/runner/work/ruby/ruby/src/test/prism/ractor_test.rb:26 [FINISH]
  c:0001 p:---- s:0003 e:000002 DUMMY  [FINISH]
  
  -- Ruby level backtrace information ----------------------------------------
  /home/runner/work/ruby/ruby/src/test/prism/ractor_test.rb:26:in 'block in test_parse_lex_file'
  /home/runner/work/ruby/ruby/src/test/prism/ractor_test.rb:26:in 'parse_lex_file'
  /home/runner/work/ruby/ruby/src/lib/prism/parse_result.rb:833:in 'initialize'
  /home/runner/work/ruby/ruby/src/lib/tempfile.rb:387:in 'call'
  
  -- Threading information ---------------------------------------------------
  Total ractor count: 2
  Ruby thread count for this ractor: 1
  
  -- C level backtrace information -------------------------------------------
  /home/runner/work/ruby/ruby/build/ruby(rb_print_backtrace+0x14) [0x561441aeedbf] ../src/vm_dump.c:843
  /home/runner/work/ruby/ruby/build/ruby(rb_vm_bugreport) ../src/vm_dump.c:1175
  /home/runner/work/ruby/ruby/build/ruby(bug_report_end+0x0) [0x561441aa3f39] ../src/error.c:1097
  /home/runner/work/ruby/ruby/build/ruby(rb_bug_without_die_internal) ../src/error.c:1097
  /home/runner/work/ruby/ruby/build/ruby(die+0x0) [0x5614416e237f] ../src/error.c:1115
  /home/runner/work/ruby/ruby/build/ruby(rb_bug) ../src/error.c:1117
  /home/runner/work/ruby/ruby/build/ruby(rb_ractor_confirm_belonging+0xde) [0x56144188c6be] ../src/ractor_core.h:376
  /home/runner/work/ruby/ruby/build/ruby(vm_exec_core+0xef) [0x5614418b23ef] /home/runner/work/ruby/ruby/build/vm.inc:2500
  /home/runner/work/ruby/ruby/build/ruby(rb_vm_exec+0x156) [0x5614418a4676] ../src/vm.c:2618
  /home/runner/work/ruby/ruby/build/ruby(vm_call0_cc+0x13d) [0x5614418aa1dd] ../src/vm_eval.c:101
  /home/runner/work/ruby/ruby/build/ruby(rb_vm_call0+0x4c) [0x5614418b1cc5] ../src/vm_eval.c:61
  /home/runner/work/ruby/ruby/build/ruby(rb_vm_call_kw) ../src/vm_eval.c:326
  /home/runner/work/ruby/ruby/build/ruby(rb_check_funcall_default_kw) ../src/vm_eval.c:694
  /home/runner/work/ruby/ruby/build/ruby(rb_gc_run_obj_finalizer+0x1cf) [0x56144170220f] ../src/gc.c:306
  /home/runner/work/ruby/ruby/build/ruby(rb_multi_ractor_p+0x0) [0x56144170246f] ../src/gc/default/default.c:2820
  /home/runner/work/ruby/ruby/build/ruby(rb_vm_lock_enter) ../src/vm_sync.h:74
  /home/runner/work/ruby/ruby/build/ruby(rb_gc_vm_lock) ../src/gc.c:137
  /home/runner/work/ruby/ruby/build/ruby(finalize_list) ../src/gc/default/default.c:2843
  /home/runner/work/ruby/ruby/build/ruby(finalize_deferred_heap_pages) ../src/gc/default/default.c:2866
```

I think it wouldn't be hard to disable that check when running a finalizer, but I don't know if it's the correct thing to do. 



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