[ruby-core:122496] [Ruby Bug#21401] ObjectSpace can't count Fibers after using a Ractor

[ruby-core:122496] [Ruby Bug#21401] ObjectSpace can't count Fibers after using a Ractor

[rmosolgo (Robert Mosolgo) via ruby-core]

Issue #21401 has been reported by rmosolgo (Robert Mosolgo).

----------------------------------------
Bug #21401: ObjectSpace can't count Fibers after using a Ractor
https://bugs.ruby-lang.org/issues/21401

* Author: rmosolgo (Robert Mosolgo)
* Status: Open
* ruby -v: ruby 3.5.0dev (2025-06-09T14:38:29Z master f9966b9b76) +PRISM [x86_64-darwin22]
* Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN
----------------------------------------
Hi, thanks for all your great work, Ruby crew!

I have a test in my project that uses `ObjectSpace.each_object(Fiber).count` to see how many Fibers have been started by my code. This test started failing when I added other tests using `Ractor`s. I was able to isolate it with this script: 


```ruby 
require "objspace"

f = Fiber.new { 1 + 1 }
GC.start

p ObjectSpace.each_object(Fiber).count
# => 2 

Ractor.new { 1 + 1 }.take

p ObjectSpace.each_object(Fiber).count
# => 0 (should be 2) 

# The fiber _is_ there!
p f 
# #<Fiber:0x0000000100c568a8 ractor_fibers.rb:4 (created)>
```

It seems like `ObjectSpace` can't count fibers for some reason, but I expect it to return the number of Fibers in memory. Other classes like `Hash` and `String` are not affected.

It fails on Ruby 3.4.1 and 3.5-dev. I used: 


- `ruby 3.5.0dev (2025-06-09T14:38:29Z master f9966b9b76) +PRISM [x86_64-darwin22]`
- `ruby 3.4.1 (2024-12-25 revision 48d4efcb85) +PRISM [x86_64-darwin22]`

Please let me know if I can help with anything else in tracking down this bug. Thanks again!





-- 
https://bugs.ruby-lang.org/
______________________________________________
 ruby-core mailing list -- ruby-core@ml.ruby-lang.org
 To unsubscribe send an email to ruby-core-leave@ml.ruby-lang.org
 ruby-core info -- https://ml.ruby-lang.org/mailman3/lists/ruby-core.ml.ruby-lang.org/

[ruby-core:122497] [Ruby Bug#21401] ObjectSpace can't count Fibers after using a Ractor

[jhawthorn (John Hawthorn) via ruby-core]

Issue #21401 has been updated by jhawthorn (John Hawthorn).

Status changed from Open to Rejected

👋 Hi Robert! This is a known issue. Once a Ractor is started `each_objects` will only return shareable objects. I expect ko1's Ractor-local GC may change this. Closing as rejected in favour of #19387.

----------------------------------------
Bug #21401: ObjectSpace can't count Fibers after using a Ractor
https://bugs.ruby-lang.org/issues/21401#change-113689

* Author: rmosolgo (Robert Mosolgo)
* Status: Rejected
* ruby -v: ruby 3.5.0dev (2025-06-09T14:38:29Z master f9966b9b76) +PRISM [x86_64-darwin22]
* Backport: 3.2: UNKNOWN, 3.3: UNKNOWN, 3.4: UNKNOWN
----------------------------------------
Hi, thanks for all your great work, Ruby crew!

I have a test in my project that uses `ObjectSpace.each_object(Fiber).count` to see how many Fibers have been started by my code. This test started failing when I added other tests using `Ractor`s. I was able to isolate it with this script: 


```ruby 
require "objspace"

f = Fiber.new { 1 + 1 }
GC.start

p ObjectSpace.each_object(Fiber).count
# => 2 

Ractor.new { 1 + 1 }.take

p ObjectSpace.each_object(Fiber).count
# => 0 (should be 2) 

# The fiber _is_ there!
p f 
# #<Fiber:0x0000000100c568a8 ractor_fibers.rb:4 (created)>
```

It seems like `ObjectSpace` can't count fibers for some reason, but I expect it to return the number of Fibers in memory. Other classes like `Hash` and `String` are not affected.

It fails on Ruby 3.4.1 and 3.5-dev. I used: 


- `ruby 3.5.0dev (2025-06-09T14:38:29Z master f9966b9b76) +PRISM [x86_64-darwin22]`
- `ruby 3.4.1 (2024-12-25 revision 48d4efcb85) +PRISM [x86_64-darwin22]`

Please let me know if I can help with anything else in tracking down this bug. Thanks again!





-- 
https://bugs.ruby-lang.org/
______________________________________________
 ruby-core mailing list -- ruby-core@ml.ruby-lang.org
 To unsubscribe send an email to ruby-core-leave@ml.ruby-lang.org
 ruby-core info -- https://ml.ruby-lang.org/mailman3/lists/ruby-core.ml.ruby-lang.org/