[PING] RFR: 8231111: Cgroups v2: Rework Metrics in java.base so as to recognize unified hierarchy

[Severin Gehwolf]

Hi Mandy,

On Thu, 2020-01-16 at 17:43 -0800, Mandy Chung wrote:
> Hi Bob, Severin,
> 
> On 1/9/20 11:51 AM, Severin Gehwolf wrote:
> > Thanks for the review! Should all be fixed now. Updated webrev:
> > 
> > incremental: 
> > http://cr.openjdk.java.net/~sgehwolf/webrevs/JDK-8231111/07/incremental/webrev/
> > full: 
> > http://cr.openjdk.java.net/~sgehwolf/webrevs/JDK-8231111/07/webrev/
>  
> This patch may be more appropriate to be reviewed by the
> serviceability group (cc'ed) as this is monitoring-related.
> 
> jdk.internal.platform.Metrics is an internal API that you are free to
> change the API as appropriate.  Given that 13 out of 38 metrics
> defined in Metrics are no longer supported by cgroups v2, it's
> cleaner to refactor Metrics interface to be implementable by cgroups
> v1 and v2 and then define a cgroups version-specific metrics to
> extend Metrics, which means that it seems reasonable to make it
> linux-only sub-interface.  Client can cast to cgroup v1 metrics
> interface if needed.  Sorry for not chiming in earlier and I am not
> following the cgroups v2 changes.  This should be a straight-forward
> change which will make the implementation cleaner.  You would no
> longer need the new *_UNLIMITED and *_NOT_SUPPORTED constants.

Like this?

Full: http://cr.openjdk.java.net/~sgehwolf/webrevs/JDK-8231111/09/webrev/
incremental: http://cr.openjdk.java.net/~sgehwolf/webrevs/JDK-8231111/09/incremental/webrev/

> A couple of quick comments when skimming on the new files:
>  CgroupSubsystemController.java
>    s/parm/param (including javadoc @param tag)
> 
> CgroupInfo.java
>    cgroupPath is not used??

Should both be fixed, thanks!

Thanks,
Severin