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

[David Holmes]

On Tue, 8 Feb 2022 08:10:05 GMT, Thomas Stuefe <stuefe 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.

Introducing a category just to collect info on a specific kind of allocation does seem somewhat fragile. I can easily imagine someone looking at ObjectMonitorHashtable and thinking it should be tagged too. But in the meantime if this serves a purpose ...

IIRC we have some existing stats we can report about ObjectMonitors if that helps.

Cheers,
David

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