RFR: 8351733: [macos] Crash when creating too many nested event loops [v3]

[Martin Fox]

On Mon, 24 Mar 2025 19:56:03 GMT, Kevin Rushforth <kcr at openjdk.org> wrote:

> > We might want to consider imposing a limit on Linux and Windows, too. It could probably be done as a follow-up...
> 
> Although doing it as part of this PR would be OK, too. Which would you prefer?

And there it is, that open can of worms.

I will put together a cross-platform version of this PR and do some testing. My first impulse was to do a focused PR that addressed the Mac-only issue reported by the customer. But if my testing is correct (I'll double-check) it looks like that same customer was within throwing distance of destabilizing the system on Windows also. And there is a testing advantage to having it be consistent across platforms.

This PR makes a distinction between nested event loops started in Platform.runLater runnables and ones started while handling an input event (the former counts against the limit and the latter doesn't). A centralized solution will probably lose that distinction but I'm not sure that's important. Exceeding 240+ nested events loops is problematic either way.

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PR Comment: https://git.openjdk.org/jfx/pull/1741#issuecomment-2749384904