RFR: 8157023: Integrate NMT with JFR [v3]

[Thomas Stuefe]

On Tue, 6 Dec 2022 13:58:36 GMT, Stefan Johansson <sjohanss at openjdk.org> wrote:

>> src/hotspot/share/services/memSnapshot.hpp line 42:
>> 
>>> 40: };
>>> 41: 
>>> 42: class MemSnapshot : public CHeapObj<mtNMT> {
>> 
>> Can we name this not Snapshot but something different? We already have MallocMemorySnapshot and methods like "as_snapshot", which have nothing to do with this layer.
>> 
>> proposals:
>> 
>> `NMTData`
>> `NMTStatistics`
>> `NMTStatSet`
>> 
>> .... 
>> ....
>
> I assume you don't think `NMTSnapshot` is good much better =) I can't come up with something much better than your suggestions, `NMTUsage` is not perfect either (sound like the usage cause by NMT). If we don't go with the NMT-prefix I think something like `MemUsage`or `NativeMemoryUsage` would make sense. Looking at the other reporting classes connected to NMT they are named `Mem`-something. So I think `MemUsage`, what do you think?

Good. Up to you.

I wish we would allow C++ namespaces, having all in something like "namespace nmt". Then it does not hurt so much if names are a bit more generic.

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PR: https://git.openjdk.org/jdk/pull/11449