RFR: 8223296: NullPointerException in GlassScene.java at line 325

[Kevin Rushforth]

On Fri, 13 Dec 2019 10:48:37 GMT, Ambarish Rapte <arapte at openjdk.org> wrote:

>>> This is moved only to make first operation when disposing. However the race condition is very rare, but this will just reduce the chances little more.
>> 
>> Can you elaborate? Why would there still be a race condition?
> 
>> Can you elaborate? Why would there still be a race condition?
> 
> Hi Kevin, Looks like I made a confusing statement.
> There won't be a race condition after this change but there can be a situation when `frameRendered()` gets executed while `dispose()` is in progress.
> Consider scenario:
> 1. `dispose()` is called on Application thread, and `setTKScenePaintListener(null)` is not executed yet.
> 2. `frameRendered()` is called on Renderer thread, and it will find that scenePaintListener is not null and `scenePaintListener.frameRendered()` call will be executed.
> 3. Then `dispose()` executes `setTKScenePaintListener(null)`
> 
> If `setTKScenePaintListener(null)` is the first operation in 'dispose()' then chances of above situation reduce little more. However the situation is very rare.
> This is to make it more sure that `scenePaintListener.frameRendered()` does not get executed once `dispose()` has begun.

OK, thanks. That's what I would have expected, but wanted to make sure there wasn't still an outstanding race condition after your fix.

This is a safe enough fix that one reviewer is sufficient.

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PR: https://git.openjdk.java.net/jfx/pull/64