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

[Kevin Rushforth]

On Wed, 11 Dec 2019 17:10:37 GMT, Ambarish Rapte <arapte at openjdk.org> wrote:

>> The change looks OK as far as it goes, meaning that it will fix the specific NPE reported by the bug and is looks like a safe fix.
>> 
>> Two questions:
>> 
>> 1. In addition to calling the synchronized `setTKScenePaintListener` method, you moved the call to the beginning of `dispose`. Is there a reason you needed to do this?
>> 2. Do any of the other listeners or variables that are set in `dispose` have the same problem (i.e., are any of the rest accessed from another thread)?
> 
>>     1. In addition to calling the synchronized `setTKScenePaintListener` method, you moved the call to the beginning of `dispose`. Is there a reason you needed to do this?
> 
> 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.
> 
>>     2. Do any of the other listeners or variables that are set in `dispose` have the same problem (i.e., are any of the rest accessed from another thread)?
> 
> Other variable do not have a race condition. All are set or accessed on JavaFX Application thread.
> There are some other variable (not in dispose()) like entireSceneDirty, painting, which are accessed on both threads but those are synchronized access.

> 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?

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