RFR: 8364516: Serial: Move class unloading logic inside SerialFullGC::invoke_at_safepoint [v4]

[Thomas Schatzl]

On Mon, 4 Aug 2025 08:13:57 GMT, Albert Mingkun Yang <ayang at openjdk.org> wrote:

>> Encapsulating classunloading logic inside `invoke_at_safepoint` and adding doc explaining why the classunloading logic can't be placed at the end of marking during full-gc, like other STW collectors.
>> 
>> Test: tier1-3
>
> Albert Mingkun Yang 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 five additional commits since the last revision:
> 
>  - Merge branch 'master' into sgc-unloading-doc
>  - review
>  - review
>  - review
>  - sgc-unloading-doc

Ship it!

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Marked as reviewed by tschatzl (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/26588#pullrequestreview-3083737607