Environment

jruby 9.2.1.0-SNAPSHOT (2.5.0) 2018-10-12 b2f694c Java HotSpot(TM) 64-Bit Server VM 25.181-b13 on 1.8.0_181-b13 +jit [linux-x86_64]

script

100.times do
  t = Thread.new do
    Kernel.sleep
    :ok
  end

  JRuby.reference(t).native_thread.interrupt
  t.value
end

JRuby.reference(t).native_thread.interrupt should stop the thread

  t = Thread.new do
    Kernel.sleep
    :ok
  end

  JRuby.reference(t).native_thread.interrupt
  => #<Thread:0x69aabcb0@(irb):31 dead>

under load (if I run it in a loop), some threads sometimes remain still in a sleep state

=> #<Thread:0x2dfeb141@(irb):39 sleep>

t.value calls Thread#join and because the thread is alive, it sleeps forever

Expected Behavior

it looks like there's a race condition somewhere? If I add a sleep call between Thread.new and thread.interrupt it won't hang. Or is it just a bad test?

100.times do
  t = Thread.new do
    Kernel.sleep
    :ok
  end

  sleep 0.25
  JRuby.reference(t).native_thread.interrupt
  t.value
end

Actual Behavior

hangs in an infinite loop

https://travis-ci.org/jruby/jruby/jobs/440880330

....
     [exec] Kernel#sleep
No output has been received in the last 10m0s, this potentially indicates a stalled build or something wrong with the build itself.
Check the details on how to adjust your build configuration on: https://docs.travis-ci.com/user/common-build-problems/#Build-times-out-because-no-output-was-received
The build has been terminated