RFR: 8367319: Add os interfaces to get machine and container values separately [v2]

[Erik Österlund]

On Mon, 27 Oct 2025 04:36:29 GMT, David Holmes <dholmes at openjdk.org> wrote:

> > is that alternative container implementation really implementing a container, or a virtual machine?
> 
> You would have to define what you mean by "container" and "virtual machine". Isolating CPU usage ala tasksets seems a natural partitioning approach for a "container" environment to me.

Not sure if me defining containers and virtual machines will take this discussion further. But for what it's worth, it is becoming popular to run a "MicroVM" instead of a container (cf. firecracker, new mac OS "containers" that are micro VMs). What it has in common with containers is that it is lightweight and starts fast. But it has dedicated hardware and you can't see the host hardware availability from it. So a perhaps more relevant question is:
1) How are these modelled today? AFAIK: they are not detected as containers.
2) How can we model these today? AFAIK: we can't get resource usage information from the host.
3) How do we want to model these today? IMO: not as containers. They quack more like virtual machines than containers and there is no obvious benefit of knowing about the world outside of the micro VM.

Regardless of these thoughts around micro VMs, I don't know if we will get far with trying to predict whether this API will fit well for a future hypothetical container system that works differently, or not. I'd vote for crossing that bridge when we get there instead, if we eventually find out then, that it could do with being updated. Does that sound good?

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PR Comment: https://git.openjdk.org/jdk/pull/27646#issuecomment-3450079013