Downport 8217338: [Containers] Improve systemd slice memory limit support

[Severin Gehwolf]

Hi Goetz!

On Fri, 2020-01-03 at 14:38 +0000, Lindenmaier, Goetz wrote:
> Hi Severin, 
> 
> I'm working on downporting the 11.0.7-oracle changes.
> https://bugs.openjdk.java.net/browse/JDK-8232207: Linux os::available_memory re-reads cgroup configuration on every invocation
> depends on 8217338.  You had once intended to downport 
> https://bugs.openjdk.java.net/browse/JDK-8217338.
> The downport was then abandoned.
> 
> I am wondering whether you want to pick this up again?

Sure, I can pick it up again. I'll try to get it done in the next week
or so.

> 8217338 is productive in 13 for a while now, and it applies
> clean.
> I'm not sure about the Java changes, do they change the API?

Not that I'm aware of. Cgroup related code is Linux only and in an
jdk.internal package.

> The hotspot changes help to apply 8232207, though.
> 
> I would like to wait with 8232207 until this is decided.

Thanks for reaching out.

Backporting 8232207 is a good idea.

Thanks,
Severin