RFR: JDK-8281460: Let ObjectMonitor have its own NMT category

[Thomas Stuefe]

On Wed, 9 Feb 2022 12:16:49 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> It would be useful to distinguish ObjectMonitor allocations in NMT, as a simple way to both to see the needed footprint as well as the number of allocated monitors.
>> 
>> Note, this needs [JDK-8281450](https://bugs.openjdk.java.net/browse/JDK-8281450) as a prerequisite.
>
> I think mtSynchronizer was for VM synchronization objects: mutexes, semaphore etc. Not ObjectMonitors. But as always if these conventions are not clearly known then "misuse" can creep in.

@dholmes-ora @shipilev Dan confirmed my original idea makes sense, are you okay with this change too?

..Thomas

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

PR: https://git.openjdk.java.net/jdk/pull/7378