RFR: 8326121: vmTestbase/gc/g1/unloading/tests/unloading_keepRef_rootClass_inMemoryCompilation_keep_cl failed with Full gc happened. Test was useless. [v2]

[Ivan Walulya]

> Hi all,
> 
> Please review this change to trigger SkippedException instead of RunTimeExceptions when a test is deemed useless because of full-GCs. The test triggers frequent `System.gc()` calls which in some cases may aggressively shrink the heap, and subsequent allocations lead to full-GC. This may affect the usefulness of the test, but it is not a test failure. So we added  SkippedException to indicate this situation.
> 
> Testing: Local testing with very small heaps.
>               Tier 1.

Ivan Walulya has updated the pull request incrementally with one additional commit since the last revision:

  Thomas Review

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/19432/files
  - new: https://git.openjdk.org/jdk/pull/19432/files/59d2462c..131fa335

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=19432&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=19432&range=00-01

  Stats: 4 lines in 2 files changed: 0 ins; 2 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/19432.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19432/head:pull/19432

PR: https://git.openjdk.org/jdk/pull/19432