Ignore VirtualThreads in jvmtiGetAllThreads and Thread.getThreads

[babsingh]

This change impacts the following methods in JDK19+:

• private static native Thread[] getThreads()
• jvmtiGetAllThreads

Virtual threads are ignored by looking at J9VMThread->carrierThreadObject
instead of J9VMThread->threadObject.

Related: #15183

Signed-off-by: Babneet Singh sbabneet@ca.ibm.com

[babsingh]

@tajila can you please review this PR?

[tajila]

jenkins test sanity amac jdk19

[tajila]

jenkins compile win jdk19

[tajila]

@babsingh youll need to rebase your changes on #15619

[babsingh]

need to rebase your changes on #15619

jvmtiGetAllThreads and Thread.getThreads are different. jvmtiGetAllThreads already uses j9jni_createLocalRef and returns the thread array and number of threads under exclusive VM access. I believe that we do not need to further update it; unless, we want to reduce the thread array size to exactly match the number of live threads during return.

[babsingh]

native Thread.getThreads will need to be updated to use carrierThreadObject since it excludes VirtualThreads and only targets platform threads: https://github.com/ibmruntimes/openj9-openjdk-jdk19/blob/4e70209d76774bab04fd17073e88c0109f3ab280/src/java.base/share/classes/java/lang/Thread.java#L2701-L2706.

[babsingh]

Updated PR to cover native Thread.getThreads. @tajila Let me know if anything was missed.

[tajila]

can you also update Java_java_lang_Thread_getThreads to return carrier threads

[babsingh]

can you also update Java_java_lang_Thread_getThreads to return carrier threads

Last Thursday's update included the carrierThreadObject changes for Java_java_lang_Thread_getThreads.

[tajila]

jenkins compile win jdk19

[tajila]

jenkins test sanity amac jdk19