RFR: JDK-8298104: NPE on synchronizeSceneNodes()

[buedi]

On Wed, 3 May 2023 11:46:50 GMT, buedi <duke at openjdk.org> wrote:

> A null pointer exception occurs on the ScenePulseListener when iterating through the dirty node list.
> A null check is needed on the node before calling node.getScene().
> 
> The error occurs occasionally and causes the application to crash.

Hello John, this issue occurs very rarely, approximately 1-2 times per month, on systems that run 24/7. However, when it does occur, the JavaFx application gets stuck in an endless loop (--> [logError-JavaFxScene.txt](https://github.com/openjdk/jfx/files/11397119/logError-JavaFxScene.txt)) and cannot recover from it. Currently, I am unable to replicate this phenomenon. I fully agree with you that it's essential to address the problem at its root cause. However, adding an additional check for a null value would at least solve a rare but blocking issue.

![sceneError_](https://user-images.githubusercontent.com/5691507/236197639-8c240ed2-d135-4abc-9a29-5d1cfa3e0984.png)

-------------

PR Comment: https://git.openjdk.org/jfx/pull/1123#issuecomment-1534664290