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

[Aleksey Shipilev]

On Mon, 20 Nov 2023 12:28:56 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`

The backport turned out to be not clean due to test modifications. @stefank, you might want to rubber-stamp this one?

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PR Comment: https://git.openjdk.org/jdk21u/pull/384#issuecomment-1820612831