RFR: 8037914: Add JFR event for string deduplication [v7]

[Erik Gahlin]

On Mon, 17 Nov 2025 13:11:32 GMT, Francesco Andreuzzi <fandreuzzi at openjdk.org> wrote:

>> In this PR I introduce a new JFR event: `jdk.StringDeduplication`
>> 
>> The new event is emitted every time a deduplication cycle happens.
>> 
>> Passes tier1 and tier2 (fastdebug).
>
> Francesco Andreuzzi has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 15 additional commits since the last revision:
> 
>  - remove elapsed. remove idle
>  - Merge branch 'master' into JDK-8037914
>  - rename. start/end time
>  - no start
>  - enable
>  - bytes to size
>  - disable
>  - revert
>  - one event
>  - trailing
>  - ... and 5 more: https://git.openjdk.org/jdk/compare/5fa84676...fc47a64e

>From a JFR perspective, this looks good. Ideally, the values of the event should be sanity-checked, but I understand this might be tricky to do in a reliable manner. Hunting down false positives would just be a waste of time. The copyright year of the test should be 2025.

It would be good if someone on the GC team could take a look at the GC-related code.

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PR Comment: https://git.openjdk.org/jdk/pull/28015#issuecomment-3542131222