RFR: 8291651: CleanerTest.java fails with "Cleanable was cleaned" [v2]

[Daniel Fuchs]

On Tue, 30 Aug 2022 18:33:24 GMT, Roger Riggs <rriggs at openjdk.org> wrote:

>> CleanerTest is failing intermittently on Aarch64, with -Xcomp, and using a VirtualThread for the Cleaner in the test.
>> The extensively relies on references processing and invokes GC on a very short cycle.
>> The existing 10ms delay between GC requests is too short for the changes to reference states to be reliably visible.
>> 
>> The delay between gc requests is extended to 200ms and the tests pass reliably.
>> There are small improvements in diagnostic messages and cleanup of unused imports.
>
> Roger Riggs has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Cleanup of messages that describe the cleaning function to be run or not.
>   Switched to using jtreg @enablePreview.

Thaks @RogerRiggs - the new messages LGTM.

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Marked as reviewed by dfuchs (Reviewer).

PR: https://git.openjdk.org/jdk/pull/10048