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

[Lindenmaier, Goetz]

Hi Severin,

> ... being pro-active about it.
I guess I was a bit too pro-active :)

But yes, I flagged jdk11u-fix-request. I think this is the 
best to do.

Best regards,
  Goetz.


> -----Original Message-----
> From: Severin Gehwolf <sgehwolf at redhat.com>
> Sent: Mittwoch, 8. Januar 2020 15:43
> To: Lindenmaier, Goetz <goetz.lindenmaier at sap.com>
> Cc: jdk-updates-dev at openjdk.java.net
> Subject: Re: Downport 8217338: [Containers] Improve systemd slice memory
> limit support
> 
> Hi Goetz!
> 
> On Wed, 2020-01-08 at 10:19 +0000, Lindenmaier, Goetz wrote:
> > Hi Severin, everybody,
> >
> > I wanted to follow your plan and let you do this downport.
> > But it was in one of my queues in between of other changes
> > that were approved and which I can push.
> > Now I accidentally pushed this change along with the others,
> > sorry!
> 
> I see. Thanks for the heads-up and being pro-active about it.
> 
> > I ran the change through our testing and it's all green.
> > But I did not request downport, so it was not approved (yet).
> > Also I thought it needs some discussion as Andrew Haley
> > had questioned it in a comment:
> > https://bugs.openjdk.java.net/browse/JDK-8217338
> > It brings some changes in internal classes in java.base.
> 
> Those changes were all in jdk.internal.platform related classes.
> Metrics.java is also Linux-only. While it changes the binary
> compatibility, I'm not sure this is a concern in practice.
> 
> > What should I do? Should I back it out, or should
> > I request downport and only back it out in case downport
> > is rejected?
> 
> I'd say request downport and if approved keep it in. It was a clean
> backport wasn't it? Also, this is in JDK 13 and I haven't heard of
> problems.
> 
> My concern originally was JDK-8227006 (and friends). With JDK-8232207
> the idea of caching for some period of time came up and paved the way
> for a fix for JDK-8227006.
> 
> Since the plan is to downport this *and* JDK-8232207 it should be fine.
> JDK-8232207 fixes the perf regression in hotspot runtime related to
> cgroups.
> 
> > Me personally am in favour of bringing the cgroup improvements
> > to 11. I think it's an important thing for Java to support.
> 
> +1
> 
> There are more changes in the pipeline, fwiw. Cgroups v2 support being
> one.
> 
> Thanks,
> Severin