FFM API allocation shootout

[Brian S O'Neill]

On 2023-07-31 04:27 PM, Maurizio Cimadamore wrote:
> 
> So, another question is:
> 
> * Do we expect a separate kind of JMX object to keep track of memory 
> segments?
> * Or do we expect the same JMX object to report stats about all kinds of 
> off-heap memory usage, whether BB or MS ?
> 
> I think having _some_ segments show up in one counter, and some other 
> segments showing up in a different counter would be odd from a 
> management perspective.
> 

If I expect that a single JMX counter should give me a complete picture, 
it won't anyhow. Allocations within native libraries won't report their 
stats using the common counter, and custom Arenas won't be able to 
either unless they can directly manipulate it.

I'd prefer many separate counters, which break down the different types 
of allocations. They have different life cycles, and so they have 
different GC effects. It would also be nice if custom counters can be 
defined.