RFR: 8305994: Guarantee eventual async monitor deflation [v6]

[Thomas Stuefe]

On Tue, 18 Apr 2023 12:20:06 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> See discussion in the bug. This PR introduces a safety rail that kicks in when the threshold heuristics fails, and it is cleanly backportable to JDK 17, where the problem manifests as apparent memory leak. There are other options to resolve this (see the bug), but I think this one is the easiest in the interim. 
>> 
>> Additional testing:
>>  - [x] Linux x86_64 `tier1`
>>  - [x] Linux x86_64 `tier2`
>>  - [x] `runtime/Monitor` tests
>>  - [x] Ad-hoc experiments (see example in the bug)
>>  - [x] New feature test
>
> Aleksey Shipilev 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 11 additional commits since the last revision:
> 
>  - Build fixes and cleanups
>  - Merge branch 'master' into JDK-8305994-async-deflate
>  - More review comments and improvements
>  - Volker is right again (fixing unsigned underflow)
>  - Sort imports
>  - Volker is right
>  - Make the no-progress bit cleaner
>  - Copyright updates
>  - Touchup the option description
>  - Test and some modifications
>  - ... and 1 more: https://git.openjdk.org/jdk/compare/36030ed6...6c887241

Looks good. Man, whats with the builds today though..

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Marked as reviewed by stuefe (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/13474#pullrequestreview-1390109423