RFR: 8369306: Implement invokeAndWait and finishTerminating on headless platform [v3]

[Andy Goryachev]

On Sat, 11 Oct 2025 09:05:45 GMT, Johan Vos <jvos at openjdk.org> wrote:

>> modules/javafx.graphics/src/main/java/com/sun/glass/ui/headless/NestedRunnableProcessor.java line 66:
>> 
>>> 64:     void stopProcessing() {
>>> 65:         for (RunLoopEntry entry : activeRunLoops) {
>>> 66:             runnableQueue.add(() -> entry.active = false);
>> 
>> I would highly recommend declaring `RunLoopEntry.active` `volatile`.
>
> Can you elaborate on this? What usecase do you see where 2 threads might see different values, leading to problems that could not occur if active was volatile?

generally speaking, when two threads modify a single boolean variable, there might be scenarios, depending on the exact hardware, when the other thread does not see the modified value right away.

some of the comments in 

https://stackoverflow.com/questions/65037547/the-volatile-keyword-and-cpu-cache-coherence-protocol
https://stackoverflow.com/questions/106591/what-is-the-volatile-keyword-useful-for

might explain it better.

-------------

PR Review Comment: https://git.openjdk.org/jfx/pull/1934#discussion_r2426770444