RFR: 8348423: [TestBug] stress test Nodes initialization from a background thread [v4]

[Kevin Rushforth]

On Fri, 31 Jan 2025 20:07:11 GMT, Kevin Rushforth <kcr at openjdk.org> wrote:

>> yes, jiggling the visible node during the test adds stress to the system, which is the intended behavior.
>
> Yes, I know. I was pointing out the fact that the frequency of the jitter will increase as the number of background threads increases. Which I think is fine.

Actually, in looking at this further, I wanted to suggest an alternative approach. Rather than having each background thread poke the application thread to run a test loop every 100 test loops of that background thread, you might consider having one additional thread whose job it is to periodically run a test loop on the app thread. With the current approach, it is likely running an app thread loop far more often than wanted for two reasons:

1. The background threads are (intentionally) free running rather than being tied to a frame or even a small sleep
2. Each background thread independently fires an FX app pass every 100 passes, meaning that if there are 20 threads, it will effectively run every 5 passes of a background thread (every 100 passes will queue up 20 calls to run a pass on the FX app thread)

Having a dedicated test thread for testing on the FX app thread would allow to control its frequency independent of the background threads.

What do you think?

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PR Review Comment: https://git.openjdk.org/jfx/pull/1690#discussion_r1939701668