RFR: JDK-8285893: Hiding dialog and showing new one causes dialog to be frozen [v6]

[Marius Hanl]

On Wed, 6 Mar 2024 17:24:10 GMT, Martin Fox <mfox at openjdk.org> wrote:

>> Marius Hanl has updated the pull request incrementally with four additional commits since the last revision:
>> 
>>  - test for multiple nested event loops
>>  - try leave outer loop after finishing inner loop
>>  - update copyright
>>  - trigger an outer nested event loop leave attempt
>
> The Mac is still failing the NestedEventLoop test.
> 
> At the top of InvokeLaterDispatcher.java there's a long explanation on how it's trying to coordinate with the event loop. To do this it needs to have an accurate picture of what's happening at the platform level. In this PR you're telling the dispatcher that an event loop has exited before the platform has actually exited the loop (before enterNestedEventLoop has returned). This is causing the dispatcher to send runLater runnables to the platform earlier than expected. On Windows the runnables will get deferred to the next event loop cycle but on Mac the runnables might get executed in the current event loop cycle. I think this is one of the "native system limitations" mentioned in the comment in InvokeLaterDispatcher.java.
> 
> I've created a branch with my proposed fix for this problem (https://github.com/beldenfox/jfx/tree/eventloopjam). The fix prevents the dispatcher from jamming when the event loop it thought was leaving enters a new loop instead. Over in the Mac Glass code I also added a comment with a few more details on what's going on.

Thanks! I feel like we are coming closer to the fix of this problem. I hopefully have time to test this much more tomorrow - I have at least "booked" myself a time slot for JavaFX. 😄

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PR Comment: https://git.openjdk.org/jfx/pull/1324#issuecomment-1984685350