On Mon, 9 Jun 2025 21:38:22 GMT, Kevin Rushforth <k...@openjdk.org> wrote:
> > I'd looked at that but it was not obvious. And it definitely is not obvious
> > that it will be the same thread that initialises the
> > MaskMarlinAlphaConsumer.java class
>
> Yes, I see what you are saying. The `ALPHA_MASK_XXX` arrays are static fields
> of `MaskMarlinAlphaConsumer`, and the renderer context class has an instance
> field of `MaskMarlinAlphaConsumer`. So it does seem possible that
> `MaskMarlinAlphaConsumer` could be initialized by a thread other than the
> prism renderer thread. Hmmm.
Fortunately, the presence of following field in RendererConext does not cause
the MaskMarlinAlphaConsumer class to be initialized:
public MaskMarlinAlphaConsumer consumer = null;
I instrumented the code, adding something that _did_ force initialization and
was able to provoke a WrongThreadException. Without my modification,
MaskMarlinAlphaConsumer doesn't get initialized until rendering.
This seems _very_ fragile, though. At best, presuming we can prove that
initialization and access to MaskMarlinAlphaConsumer always happens on the
Prism rendering thread, this is an accident waiting to happen.
@bourgesl Do you have any thoughts on this? Using the shared arena is
definitely safer, but there might be a performance penalty.
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PR Comment: https://git.openjdk.org/jfx/pull/1814#issuecomment-2957147725
