[MacRuby-devel] macruby GCD bug?

Watson watson1978 at gmail.com
Fri Jan 13 06:12:47 PST 2012


Hi,

it looks like the variable's scope issue.
I don't know detail why this crash happen yet.

for workaround, you could use variable $array or @array instead of array.


Thanks,

2012/1/13 Alan Skipp <al_skipp at fastmail.fm>:
> I've been continuing with my efforts to implement Fibers using GCD and in the process I think I may have uncovered a Macruby bug - though perhaps it's a bug in my code? Is there anything fundamentally wrong with the code posted below? It consistently results in a EXC_BAD_ACCESS error.
>
> Cheers,
> Al
>
> class Fiber
>  def initialize &block
>    @block = block
>
>    @yield_sem = Dispatch::Semaphore.new(0)
>    @resume_sem = Dispatch::Semaphore.new(0)
>
>    @fiber_queue = Dispatch::Queue.new "fiber"
>    @fiber_queue.async {@yield_sem.wait} # immediately suspend @fiber_queue
>
>    # the following block will only run after '@yield_sem' is signalled – which happens when 'resume' is called
>    @fiber_queue.async do
>      @block.call
>      @resume_sem.signal # the block has finished - let the caller resume
>    end
>  end
>
>  def resume
>    @yield_sem.signal
>    @resume_sem.wait # causes the GCD queue of the caller to suspend
>  end
> end
>
> array = [1,2,3]
> fiber = Fiber.new { array << 4 } # crash when fiber is resumed
> fiber.resume
> p array # we don't get this far
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