support Ractor #75

ko1 · 2025-12-05T00:57:30Z

Introduce DATA to store all status.
Store DATA instance to the Ractor local storage if possible
Make GET_TIME (Method object) shareable if possible

3 is supporeted Ruby 4.0 and later, so the Rator support is works only on Ruby 4.0 and later.

eregon

I commented on some surface-level things.

In general its' not great we need extra indirections and hurt readability this way for Ractor :/
I'm also concerned about performance, could you run #15 (comment) before and after this change?

lib/timeout.rb

eregon · 2025-12-05T11:16:48Z

From a design POV it's not ideal to have potentially 1 Timeout thread per Ractor, especially with many Ractors, as that can double the number of threads if Timeout is used in every Ractor.
It would be probably better to have 1 Timeout thread per Ruby process.
OTOH I guess that's probably not really feasible, as we'd need to Thread#raise from a Thread in a different Ractor, and also the implementation would be complicated, so this approach of 1 Timeout thread per Ractor makes sense for now and is simpler.

ko1 · 2025-12-05T11:25:13Z

From a design POV it's not ideal to have potentially 1 Timeout thread per Ractor, especially with many Ractors, as that can double the number of threads if Timeout is used in every Ractor. It would be probably better to have 1 Timeout thread per Ruby process. OTOH I guess that's probably not really feasible, as we'd need to Thread#raise from a Thread in a different Ractor, and also the implementation would be complicated, so this approach of 1 Timeout thread per Ractor makes sense for now and is simpler.

Yes. See my slide: https://rubykaigi.org/2024/presentations/ko1.html (my trial and not matured on API)

eregon · 2025-12-05T11:47:14Z

Yes. See my slide: https://rubykaigi.org/2024/presentations/ko1.html (my trial and not matured on API)

Thanks, I hadn't seen those.
So this is solution 1.
Solution 2 would need something like Ractor#interrupt_exec but also be able to pass Thread references (of other Ractors) around, so yeah seems hard.
Solution 3 to make Timeout core would make sense, but it seems not enough time before Ruby 4.0.

So yeah, I think solution 1 makes sense for now.

eregon · 2025-12-05T11:50:42Z

I think after addressing my comments above and simplifying the changes now that everything can be defined as singleton methods and not module_function this PR will probably look good enough to me to merge and I'll re-review then.

eregon · 2025-12-05T11:55:19Z

lib/timeout.rb

-  TIMEOUT_THREAD_MUTEX = Mutex.new
-  @timeout_thread = nil
-  private_constant :CONDVAR, :QUEUE, :QUEUE_MUTEX, :TIMEOUT_THREAD_MUTEX
+  DATA = Struct.new(*%i{condvar queue queue_mutex timeout_thread_mutex timeout_thread})


I'm thinking this should be named State since it is the state of this library.
As a bonus it respects normal naming for classes (CamelCase) without conflicting with ::Data

ko1 · 2025-12-05T16:52:59Z

Thank you for the review and I'd merged your idea.

DATA -> State class
- move create_timeout_thread and ensure_timeout_thread_created into State and we don't need to expose @timeout_thread and TIMEOUT_THREAD_MUTEX. We don't need to introduce private methods for Timeout module.
remove get_data and introduce State.instance to acquire the State instance.

I think it is much simpler.

For the performance, on my machine the measurement doesn't stable.

Maybe I think we clear all of concerns. If there is no big issue, we can merge it and apply another fixes in future.

ko1 · 2025-12-05T17:16:18Z

lib/timeout.rb

+
+  # We keep a private reference so that time mocking libraries won't break
+  # Timeout.
+  GET_TIME =


we can shorten them for example with

m = Process.method(:clock_gettime) GET_TIME = (defined?(Ractor.make_shareable) && Ractor.make_shareable(m) rescue m) || m

but it is cosmetic issue (and difficult to understand by a glance).

This looks fine. It could also be:

GET_TIME = Process.method(:clock_gettime) Ractor.make_shareable(GET_TIME) rescue nil # Only works on Ruby 4+

Actually, would just GET_TIME = Process.method(:clock_gettime).freeze work and be enough? That seems nicest.

Actually, would just GET_TIME = Process.method(:clock_gettime).freeze work and be enough?

I tried but it does not work, it's not detected as shareable.
I thought it should work though for objects which use RUBY_TYPED_FROZEN_SHAREABLE (or RUBY_TYPED_FROZEN_SHAREABLE_NO_REC in this case).
Possibly a bug or is it my misunderstanding that.freeze should make such object shareable?

1. Introduce State to store all status. 2. Store State instance to the Ractor local storage if possible 3. Make `GET_TIME` (Method object) shareable if possible 3 is supporeted Ruby 4.0 and later, so the Rator support is works only on Ruby 4.0 and later.

eregon · 2025-12-05T18:05:38Z

lib/timeout.rb

+
+       ::Timeout::RACTOR_SUPPORT = true # for test
+    else
+      @GLOBAL_STATE = State.new


Suggested change

@GLOBAL_STATE = State.new

GLOBAL_STATE = State.new

A constant should be faster (at least with JIT)

eregon · 2025-12-05T18:09:09Z

move create_timeout_thread and ensure_timeout_thread_created into State and we don't need to expose @timeout_thread and TIMEOUT_THREAD_MUTEX. We don't need to introduce private methods for Timeout module.

That's a great idea, it looks much cleaner now because these methods can then just access @ivars directly vs having to state.foo everywhere.

eregon

This looks good to me, I will just push some tiny changes on top and then I'll merge this.

* Fix indentation to stay a multiple of 2 spaces.

eregon · 2025-12-05T18:31:08Z

All good now, there was a small bug which I fixed as well (see extra commits).

eregon · 2025-12-05T19:37:04Z

@hsbt I would like to make a release of timeout from current master, is that OK?
See also ruby/ruby#15424

Is the process just bumping VERSION in lib/timeout.rb, commit, tag it and push both commit & tag and the rest is automatic?

luke-gruber · 2025-12-05T21:53:03Z

As for having a single timeout thread, I think we would need Ractor.receive that takes an optional timeout argument, and to interrupt threads in different ractors, like you said. Maybe writing it in C and making it core would be better.

hsbt · 2025-12-08T07:11:17Z

Released https://github.com/ruby/timeout/releases/tag/v0.5.0