RFR: 8351484: Race condition in max stats in MonitorList::add [v2]

[Zhengyu Gu]

On Mon, 10 Mar 2025 19:37:21 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> See bug for the description of the race. New gtest test case reliably catches fire on my 5950X desktop without this fix.
>> 
>> I needed to add the proper constructor for `MonitorList` to make it testable. In our regular code, it is statically allocated, so its fields are implicitly initialized.
>> 
>> I also made counter updates `_relaxed` for completeness.
>> 
>> Additional testing:
>>  - [x] Linux x86_64 server fastdebug, new test now passes
>>  - [x] GHA
>
> Aleksey Shipilev has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - Can check <=
>  - Object handle

LGTM

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Marked as reviewed by zgu (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/23961#pullrequestreview-2672468427