RFR: 8339561: The test/jdk/java/awt/Paint/ListRepaint.java may fail after JDK-8327401 [v6]

[Alexey Ivanov]

On Wed, 16 Apr 2025 22:36:50 GMT, Sergey Bylokhov <serb at openjdk.org> wrote:

>>> I think as of now it should be good enough
>> 
>> That's the problem, the presence of the `volatile` modifier creates a false sense of thread-safety, this is why I'd rather not add it.
>> 
>>> why do you think volatile will not help here?
>> 
>> The `volatile` modifier guarantees that a thread which reads from the `volatile` field will see everything that occurred before a (new) reference was written to the `volatile` field. Yet there are no guarantees another thread will see any modifications to fields of the object the reference to which is stored in the `volatile` field.
>> 
>> And this test does exactly this: it writes a reference into the `currentState` field and then it modifies the fields of the object stored in `currentState`. There are no guarantees that `currentState.setAction(true)` will result in `currentState.getAction()` returning `true`.
>> 
>> If you also declare `TestState.action` as `volatile` or use `AtomicBoolean`, it could be enough to safely access the `currentState` field from two threads. Other fields are final, so they can't be modified, and therefore they don't change after another thread sees the reference to `TestState` object.
>
> @aivanov-jdk Do you have any other comments?

Sorry, for the delay, I've been busy recently. I'll take another look as soon as possible. Thank you for your understanding.

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PR Review Comment: https://git.openjdk.org/jdk/pull/20861#discussion_r2048598821