On Thu, 27 Mar 2025 15:21:09 GMT, Martin Fox <m...@openjdk.org> wrote:

>> There is an undocumented limit on nesting calls to CFRunLoopRun (or the 
>> equivalent wrapper NSRunLoop methods). When the limit is hit the OS 
>> terminates the Java app. The situation arises when a JavaFX app creates too 
>> many nested event loops from within  Platform.runLater runnables.
>> 
>> This PR doesn't change the limit (which is 250+ nested loops) but it does 
>> throw an exception just before the limit is reached so a JavaFX developer 
>> will get a useful Java stack trace instead of an OS crash log.
>> 
>> On the Mac the nested event loop has two stages: first we ask the run loop 
>> to run, then we pull an event out and process it. A Platform.runLater 
>> runnable is executed in the first stage so if the runnable starts a new 
>> nested event loop the system will re-enter CFRunLoopRun. The same isn't true 
>> if an input event handler starts a new nested event loop; at that point 
>> we're in stage two and are past the call to CFRunLoopRun.
>
> Martin Fox has updated the pull request incrementally with two additional 
> commits since the last revision:
> 
>  - Removed unnecessary import
>  - The max nested event loop constant is no longer public

This needs a second reviewer. It will likely need a CSR since there is a new 
exception being documented and throws.

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PR Comment: https://git.openjdk.org/jfx/pull/1741#issuecomment-2758851795

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