From: "ko1 (Koichi Sasada) via ruby-core" <ruby-core@...>
Date: 2026-09-09T02:35:17+00:00
Subject: [ruby-core:126602] [Ruby Bug#19387] ObjectSpace.each_objects only returns shareable objects after starting a Ractor

Issue #19387 has been updated by ko1 (Koichi Sasada).

Status changed from Assigned to Closed

Re-checked on master 4d185cce78: this no longer reproduces.

With per-Ractor GC (GH-18194) each Ractor has its own objspace, and
`ObjectSpace.each_object` walks the calling Ractor's objspace directly, so it keeps
working while other Ractors are alive:

    port = Ractor::Port.new
    r = Ractor.new(port) { |p| p << :up; Ractor.receive }
    port.receive
    p ObjectSpace.each_object(IO).count

    ruby 4.0.2 : 0
    master     : 3

Isolation is still respected. Letting a sub-Ractor build one unshareable and one
shareable String and scanning for them from the main Ractor:

                                          4.0.2    master
    own unshareable objects                no       yes
    another Ractor's unshareable objects   no       no
    another Ractor's shareable objects     yes      yes

(the last row needs the object to have actually been made shareable; a merely frozen
String that nobody has shared yet does not carry the flag and is not enumerated.)

So the reported symptom -- `each_object` yields nothing once a Ractor has been started
-- is gone, and `Ractor.new` can be used in `make test-all` again.

One follow-up: the documentation added in GH-13278 ("Due to a current Ractor
implementation issue, this method does not yield Ractor-unshareable objects when the
process is in multi-Ractor mode", which links to this ticket) is now wrong. I will send
a separate PR for it.

----------------------------------------
Bug #19387: ObjectSpace.each_objects only returns shareable objects after starting a Ractor
https://bugs.ruby-lang.org/issues/19387#change-118831

* Author: luke-gru (Luke Gruber)
* Status: Closed
* Assignee: ractor
* ruby -v: 3.3.0
* Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN
----------------------------------------
```ruby
r = Ractor.new do
  receive # block, the problem is not the termination of the ractor but the starting
end

ObjectSpace.each_object(IO) { |io|
  p io # we get no objects
}
```





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