Environment Information
JRuby version: 10.0.4.0, 10.0.3.0
Operating system: Linux burza 6.19.6-arch1-1 #1 SMP PREEMPT_DYNAMIC Wed, 04 Mar 2026 18:25:08 +0000 x86_64 GNU/Linux, but also on MacOS
Expected Behavior
The script below behaves the same way in MRI and JRuby.
fiber = Fiber.new do
begin
Fiber.yield(:a)
rescue RuntimeError
end
Fiber.yield(:b)
:done
end
fiber.resume
fiber.raise(RuntimeError.new("oh no!"))
p fiber.resume(:c)Actual Behavior
On MRI (checked 3.4.7 and 4.0.1):
On JRuby:
FiberError: attempt to resume a resuming fiber
resume at org/jruby/ext/fiber/ThreadFiber.java:187
<main> at fiber_raise.rb:12
RuntimeError: oh no!
raise at org/jruby/ext/fiber/ThreadFiber.java:401
raise at org/jruby/ext/fiber/ThreadFiber.java:232
<main> at fiber_raise.rb:11
This was found while attempting to make dry-effects JRuby-compatible. Example CI run: https://github.com/dry-rb/dry-effects/actions/runs/21515027891/job/61991147407
Environment Information
JRuby version: 10.0.4.0, 10.0.3.0
Operating system: Linux burza 6.19.6-arch1-1 #1 SMP PREEMPT_DYNAMIC Wed, 04 Mar 2026 18:25:08 +0000 x86_64 GNU/Linux, but also on MacOS
Expected Behavior
The script below behaves the same way in MRI and JRuby.
Actual Behavior
On MRI (checked 3.4.7 and 4.0.1):
On JRuby:
This was found while attempting to make dry-effects JRuby-compatible. Example CI run: https://github.com/dry-rb/dry-effects/actions/runs/21515027891/job/61991147407