RFR: 8357650: ThreadSnapshot to take snapshot of thread for thread dumps [v2]

[Serguei Spitsyn]

On Tue, 27 May 2025 22:48:15 GMT, Alex Menkov <amenkov at openjdk.org> wrote:

>> This is first (hotspot) part of the update for `HotSpotDiagnosticMXBean.dumpThreads` and `jcmd Thread.dump_to_file` to include lock information in thread dumps (JDK-8356870).
>> The update has been split into parts to simplify reviewing.
>> The fix contains an implementation of `jdk.internal.vm.ThreadSnapshot` class to gather required information about a thread.
>> Second (dependent) part includes changes in `HotSpotDiagnosticMXBean.dumpThreads`/`jcmd Thread.dump_to_file`, spec updates and tests for the functionality.
>> 
>> Testing: new `HotSpotDiagnosticMXBean.dumpThreads`/`jcmd Thread.dump_to_file` functionality was tested in loom repo;
>>   sanity tier1 (this fix only)
>
> Alex Menkov has updated the pull request incrementally with one additional commit since the last revision:
> 
>   move to ThreadService

src/hotspot/share/prims/jvm.cpp line 2968:

> 2966:   oop snapshot = VMThreadSnapshot::get_thread_snapshot(jthread, THREAD);
> 2967:   return JNIHandles::make_local(THREAD, snapshot);
> 2968: #elif

Q: should it be `#else` instead of `#elif`?

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PR Review Comment: https://git.openjdk.org/jdk/pull/25425#discussion_r2111519744