RFR: 8341913: Support CDS heap dumping for Shenandoah and Epsilon

[Aleksey Shipilev]

On Thu, 10 Oct 2024 16:33:46 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> This follows [JDK-8298614](https://bugs.openjdk.org/browse/JDK-8298614) and completes support for CDS dumping for Shenandoah and Epsilon. We have already enabled these in Leyden repo. I took a chance to clean up the code a bit. Shenandoah support is tested by the existing test. Epsilon support was tested manually, since it is quite likely flaky (= depends on pre-dump conditions not to run into OOM) to include in tests.
> 
> Additional testing:
>  - [x] Linux x86_64 fastdebug server, `runtime/cds`
>  - [x] Linux x86_64 fastdebug server, `runtime/cds`, `-XX:+UseShenandoahGC`
>  - [x] Linux x86_64 fastdebug server, manual dumps with `-XX:+UseEpsilonGC`

Attn @iklam :)

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PR Comment: https://git.openjdk.org/jdk/pull/21457#issuecomment-2427463347