CRIU Support Documentation Updates for 0.40

[dsouzai]

Overview:

• Describe JITServer behaviour changes wrt to CRIU (Enable JITServer post-restore only if explicitly specified openj9#17205)

Release target:
Eclipse OpenJ9 0.40.0*

Applies to the following JDK versions:
JDKs that implement OpenJ9 CRIU Support

Applies to the following platforms:
Linux only on x96, P, Z

[dsouzai]

I'm opening this issue mainly as a placeholder to catch all changes in the behaviour of the OpenJ9 CRIU Support feature post 0.38.

[Sreekala-Gopakumar]

@dsouzai - Any further updates in this issue? Thanks!

[dsouzai]

No other updates, this is the only change from the JIT side for 0.40. @JasonFengJ9 may have other updates though for the VM.

[JasonFengJ9]

There are a couple of VM updates in progress, one is CRIU throws JVMCRIUException in single threaded mode if parks no timeout, the other one is to adjust VirtualThread.DEFAULT_SCHEDULER.PARALLELISM for carrier thread scheduling according to Runtime.availableProcessors().
Will provide details after the PR approval/merge.

[Sreekala-Gopakumar]

There are a couple of VM updates in progress, one is CRIU throws JVMCRIUException in single threaded mode if parks no timeout, the other one is to adjust VirtualThread.DEFAULT_SCHEDULER.PARALLELISM for carrier thread scheduling according to Runtime.availableProcessors().
Will provide details after the PR approval/merge.

Is this change approved and merged as yet (I can see that this PR is not closed)?

[JasonFengJ9]

Is this change approved and merged as yet (I can see that this PR is not closed)?

Not yet, also opened

• CRIU resets j.l.VirtualThread.ForkJoinPool.parallelism after restore openj9#17618

[Sreekala-Gopakumar]

Is this change approved and merged as yet (I can see that this PR is not closed)?

Not yet, also opened

• CRIU resets j.l.VirtualThread.ForkJoinPool.parallelism after restore openj9#17618

ok. I will take this up after it is merged (as per the Contribution guidelines).

Any update on this?

[Sreekala-Gopakumar]

@JasonFengJ9 - The following issues seem more like API doc changes. So, I can skip these since I am documenting user docs?

eclipse-openj9/openj9#17618 and eclipse-openj9/openj9#17573

[JasonFengJ9]

• CRIU resets j.l.VirtualThread.ForkJoinPool.parallelism after restore openj9#17618
  is not in the main branch yet.

• CRIU throws JVMCRIUException in single threaded mode if parks no timeout openj9#17573
  is an internal implementation change, no user doc update is required.

So, I can skip these since I am documenting user docs?

Right