[GR-44559] Finish `ThreadMXBean` implementation for Native Image.

[fniephaus]

SubstrateThreadMXBean implements com.sun.management.ThreadMXBean for Native Image and is not fully implemented yet, for example:

graal/substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/jdk/management/SubstrateThreadMXBean.java

Lines 149 to 172 in 7268f71

	@Override
	public long[] getAllThreadIds() {
	throw VMError.unsupportedFeature(MSG);
	}
	@Override
	public ThreadInfo getThreadInfo(long id) {
	throw VMError.unsupportedFeature(MSG);
	}
	@Override
	public ThreadInfo[] getThreadInfo(long[] ids) {
	throw VMError.unsupportedFeature(MSG);
	}
	@Override
	public ThreadInfo getThreadInfo(long id, int maxDepth) {
	throw VMError.unsupportedFeature(MSG);
	}
	@Override
	public ThreadInfo[] getThreadInfo(long[] ids, int maxDepth) {
	throw VMError.unsupportedFeature(MSG);
	}

To improve JMX support (#4732), some of these methods throwing VMError.unsupportedFeature() will be switched to return reasonable, but empty default values (e.g., new ThreadInfo[0]). While this allows some JMX tools to work, some key functionality of ThreadMXBean is still missing and needs to be implemented.

[oeresundsgruppen]

Will this be in v23 ?

[fniephaus]

Will this be in v23 ?

@oeresundsgruppen unfortunately no and we still haven't found anyone who has the time to work on this.

[smthelusive]

@fniephaus I would like to help! Can I pick it up?

[fniephaus]

I would like to help! Can I pick it up?

Sure, feel free to take a look and let me know if you need any help. :)

[smthelusive]

Hi @fniephaus! I have created this PR, please take a look when you have time 🙂

[smthelusive]

Hi @selhagani, I am no longer working on this, please see the comments in the PR.