On Mon, 9 Jun 2025 21:23:47 GMT, Phil Race <p...@openjdk.org> wrote: > > > Multi-threaded access in the sense of the not being used concurrently by > > > different threads ? What FFM means is that the thread that creates the > > > Arena is the only thread ever allowed to use the Arena or any memory > > > allocated by it. I don't quite see how you guarantee a static field of a > > > class is never accessed by another thread. And all it takes is for some > > > other thread to have initialize the class and boom > > > And how in fact is Marlin ensuring only one thread is ever used to run > > > Marlin ? I didn't think it did anything of the kind. Is this just a case > > > of the FX thread always runs it ? > > > > > > The QuantumRenderer thread uses Marlin during rendering and the JavaFX > > application thread uses it during picking. > > @bourgesl can provide a more complete answer, but from what I see, all > > accesses to OffHeapArray are done via an instance of the RendererContext > > class. Marlin ensures that a RendererContext instance is created and > > accessed on the same thread by using thread local state and using the > > rendering context for the thread in question (or creating it if it is the > > first time). See > > [DMarlinRenderingEngine::getRendererContext](https://github.com/openjdk/jfx/blob/b22ed6d202f7bb3765fa402a748d455f6316f7c9/modules/javafx.graphics/src/main/java/com/sun/marlin/DMarlinRenderingEngine.java#L254). > > 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. ------------- PR Comment: https://git.openjdk.org/jfx/pull/1814#issuecomment-2957097495
