RFD: Remove Hotspot-internal MBeans from sun.management

[mandy.chung at oracle.com]

> Would a PR to remove these APIs be welcome?
>

Good with me.

Mandy

On 3/19/24 9:41 AM, Eirik Bjørsnøs wrote:
>
> Hi,
>
> Last September, Volker shared the observation that we have 
> Hotspot-internal MBeans in sun.management which are strongly 
> encapsulated and not used internally by OpenJDK besides their unit tests:
>
> https://www.mail-archive.com/core-libs-dev@openjdk.org/msg19878.html 
> <https://urldefense.com/v3/__https://www.mail-archive.com/core-libs-dev@openjdk.org/msg19878.html__;!!ACWV5N9M2RV99hQ!KfW2PiXn5Gb38tJmxUNxLW_fhwy1H7NijeBmgeWH0ZWNw6QriJmDY_ZD5miuxMQq9q0Rl_k6ZOdb-b0$>
>
> A summary of the email thread:
>
> Mandy pointed out:
>
>     We added these HotSpot internal MBeans in JDK 5 to expose the
>     internal metrics.  Most of these internal metrics are exposed via
>     jstat tool too.   We didn't receive much feedback regarding these
>     HotSpot internal MBeans.    Removing them is fine and good cleanup
>     effort.
>
>
> Alan made a similar point:
>
>     It's left over from experiments on exposing some internal metrics,
>     I think during JDK 5. It's code that should probably have been
>     removed a long time ago.
>
>
> Kirk P raised a concern:
>
>     It would be a shame to lose these metrics because many of them
>     have been very
>     useful over time and some would be even more useful with some
>     modifications.
>
> To which Mandy responded:
>
>     What we're referring to is to remove sun.management.Hotspot*, the
>     internal MBeans which are never exposed and registered in the
>     platform MBeanServer.   The internal metrics in HotSpot VM should
>     be retained as they are exposed through other ways like jstat, GC
>     logs, etc.
>
>
> The email thread seems to have ended here without further action taken.
>
> My interpretation of the above is that we have a consensus that these 
> Hotspot-internal MBeans can be removed. Since I was not part of the 
> initial discussion and some time has passed, I'd like some 
> confirmation that my interpretation is correct.
>
> Would a PR to remove these APIs be welcome?
>
> (This would remove HotspotInternalMBean, HotspotMemoryMBean, 
> HotspotRuntimeMBean, HotspotThreadMBean, with associated 
> implementation, factory methods, tests and probably also some native 
> code in libmanagement. Details can be discussed in a PR)
>
> Cheers,
> Eirik.
>
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