RFR: ThreadSnapshot: redesign and cleanup [v2]

[Alex Menkov]

On Fri, 16 May 2025 06:52:53 GMT, Alan Bateman <alanb at openjdk.org> wrote:

>> Alex Menkov has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   ELIMINATED
>
> src/hotspot/share/classfile/javaClasses.cpp line 1974:
> 
>> 1972:         oop park_blocker = java_lang_Thread::park_blocker(_java_thread());
>> 1973:         if (park_blocker != nullptr) {
>> 1974:           _blocker = LockInfo(LockInfo::PARKING_TO_WAIT, OopHandle(Universe::vm_global(), park_blocker));
> 
> At some point then maybe this could move out of detect_locks as it's nothing to do with the javaVFrame, instead parkBlocker is just a property of a thread and PARKING_TO_WAIT can be PARK_BLOCKER.

Added to TODO list

> src/java.base/share/classes/jdk/internal/vm/ThreadSnapshot.java line 37:
> 
>> 35:     private static final ThreadLock[] EMPTY_LOCKS = new ThreadLock[0];
>> 36: 
>> 37:     // filled by VM
> 
> At some point we need to add carrierThread to also be captured when the target thread is a mounted virtual thread.

Added to TODO list

-------------

PR Review Comment: https://git.openjdk.org/loom/pull/220#discussion_r2093514374
PR Review Comment: https://git.openjdk.org/loom/pull/220#discussion_r2093514529