RFR: 8365057: Add support for java.util.concurrent lock information to Thread.dump_to_file [v5]

[Alan Bateman]

On Thu, 25 Sep 2025 19:40:40 GMT, Alex Menkov <amenkov at openjdk.org> wrote:

>> The fix updates `jcmd Thread.dump_to_file`/`HotSpotDiagnosticMXBean.dumpThreads` implementation to report thread which owns parkBlocker.
>> 
>> Testing: tier1..4,hs-tier5-svc
>
> Alex Menkov has updated the pull request incrementally with one additional commit since the last revision:
> 
>   feedback

Aside from the issues with the method comments in the DumpThreads test, I think this is okay and I don't have other comments.

As per the discussion in the JBS issue, it's still a bit icky to read this field when all access is plain access, but it may be useful for diagnosing hangs and deadlocks.

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Marked as reviewed by alanb (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/27457#pullrequestreview-3270352643