RFR: 8351996: Behavioral updates for ClassValue::remove [v8]

[Jaikiran Pai]

On Mon, 28 Apr 2025 04:12:03 GMT, Chen Liang <liach at openjdk.org> wrote:

>> The recent patch #23866 makes calling `ClassValue::remove()` from `ClassValue::computeValue()` end up in infinite loops while fixing the stale value risk from the method.
>> 
>> The proposed fix is to preserve the stale value risk fix, and update the remove-from-compute behavior from the original designated no-op behavior to throwing an exception, as the original behavior conflicts with the stale value fix.
>> 
>> The implementation track the owner thread in promises (accessed in locked section); as a result, we can fail-fast on recursive removals from `computeValue`. I did not choose to use `ThreadTracker` as it is designed for single tracker and multiple threads, while this case here sees often just one thread, and the threads outlive the promise objects.
>> 
>> Also updated the API specs for `remove` to more concisely describe the memory effects. Please review the associated CSR as well.
>
> Chen Liang has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Test updates - remove repetition, test case for no stale installation

Hello Chen, my experience with ClassValue is non-existent. I'll however review this in the coming days and take a look at that class and the discussions here and other places. If in the meatime you do receive an approval of these changes, then please do go ahead without waiting for mine.

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PR Comment: https://git.openjdk.org/jdk/pull/24043#issuecomment-2835320393