RFR: 8341913: Support CDS heap dumping for Shenandoah and Epsilon [v2]

[Ioi Lam]

On Tue, 22 Oct 2024 07:28:17 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`
>
> Aleksey Shipilev has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Wrap test with Shenandoah check

test/hotspot/jtreg/runtime/cds/appcds/sharedStrings/IncompatibleOptions.java line 116:

> 114:         if (GC.Shenandoah.isSupported()) {
> 115:             testDump(4, "-XX:+UseShenandoahGC", "", "", false);
> 116:         }

I didn't realize that Epsilon is also included in this PR. Should we add a test case for Epsilon as well?

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PR Review Comment: https://git.openjdk.org/jdk/pull/21457#discussion_r1810996898