[jdk21u] RFR: 8318757: VM_ThreadDump asserts in interleaved ObjectMonitor::deflate_monitor calls [v2]

[Aleksey Shipilev]

On Tue, 21 Nov 2023 10:17:47 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> Fixes an important race condition in monitor deflation code. Applies cleanly, but the test needs `-XX:+UnlockExperimentalVMOptions` to unlock `-XX:LockingMode=0`.
>> 
>> Additional testing:
>>  - [x] MacOS AArch64 fastdebug, new regression test fails without the fix, passes with it
>>  - [x] Linux AArch64 fastdebug `tier1 tier2 tier3 tier4`
>
> Aleksey Shipilev has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Unlock LockingMode properly

Closing in favor of eventual backport against jdk21u-dev.

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PR Comment: https://git.openjdk.org/jdk21u/pull/384#issuecomment-1863410147