RFR [14]: 8232207: Linux os::available_memory re-reads cgroup configuration on every invocation

[Severin Gehwolf]

On Tue, 2019-10-15 at 20:04 +0200, Claes Redestad wrote:
> > Note that from an OpenShift perspective, config changes == container
> > restart, ergo JVM restart. So there is no point in actually re-reading
> > the limits.
> 
> This is an interesting data point. I've always been curious where the
> requirement originated that says the JVM container support must adjust
> dynamically to container configuration changes?

I'm not sure where this comes from. Comments in JDK-8227006 have some
details. With that said, it's entirely possible I don't have all the
info/requirements at hand.

> If the typical scenario is a static configuration then perhaps that
> would have been a better default. A fully adaptive mode (with the
> overheads that comes) sounds like something that should be an opt-in.

+1 on fully adaptive mode should be opt-in.

IIRC, the premise was that "we cannot prove that the config stays
static in all cases". Hence, the adaptive mode conclusion. I'm in no
way in that court, though.

Thanks,
Severin