Error swallowed inside second task if the first task runs a loop

[kwboyd-shopify]

Hi! I'm running into an issue when using Async::Barrier with two infinitely running loops. When I raise a StandardError inside the second task, that task stops, but the barrier continues running the first task, despite me running barrier.wait and ensuring barrier.stop. When I raise a StandardError inside the first task, that ensure block does get hit and the barrier does stop both tasks.

Here's a short reproduction of the issue:

require "async"
require "async/barrier"
class Runner
  def run
    barrier = Async::Barrier.new

    Async do
      barrier.async(annotation: "Loop 1") do
        loop do
          puts "Running loop 1"
          sleep(1)
                    
          # This error will bring us to the `ensure` block and stops the barrier
          # raise "Error 1"
          sleep(1)
        end
      end

      barrier.async(annotation: "Loop 2") do
        loop do
          puts "Running loop 2"
          sleep(1)

          # This error will bring NOT us to the `ensure` block and does not stop the barrier
          raise "Error 2"
          sleep(1)
        end
      end

      begin
        barrier.wait
      ensure
        puts "Stopping barrier"
        barrier.stop
      end
    end
  rescue StandardError, Exception => e
    raise e
  end
end

Runner.new().run

This only seems to occur if the first task runs an infinite loop. The second task running in a loop or not doesn't affect the outcome.

I found a few workarounds:

1. Having the second task raise an Exception instead
2. Adding barrier.stop if barrier.tasks.to_a.any? { |node| !node.task.alive? } inside the loop of the first task

Thanks in advance for any insight!