[jdk8u-dev] RFR: 8231111: Cgroups v2: Rework Metrics in java.base so as to recognize unified hierarchy [v4]

[Jonathan Dowland]

> This is a backport of [4def210a22faaec6b47912dd314e6365ea48d28f](https://github.com/openjdk/jdk/commit/4def210a22faaec6b47912dd314e6365ea48d28f) for jdk8u-dev as part of an effort to backport cgroups v2 support.
> 
> It does not apply clean. Paths need unshuffling. A number of changes were needed for 8u support. I've structured the PR as separate commits, with each change made in a separate commit for (hopefully) ease of review.
> 
> Not all the new tests pass:     TestDockerMemoryMetrics  failing one, specifically:
> 
>     Exception in thread "main" java.lang.RuntimeException: Memory and swap limit not equal, expected : [209715200, 1073741824], got : [209715200, 864026624]
> 
> I think this is fixed in a further patch to backport, and will confirm.

Jonathan Dowland has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains one additional commit since the last revision:

  Address style nit

-------------

Changes:
  - all: https://git.openjdk.org/jdk8u-dev/pull/121/files
  - new: https://git.openjdk.org/jdk8u-dev/pull/121/files/0ea3c608..d0352fcf

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk8u-dev&pr=121&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk8u-dev&pr=121&range=02-03

  Stats: 8 lines in 2 files changed: 0 ins; 0 del; 8 mod
  Patch: https://git.openjdk.org/jdk8u-dev/pull/121.diff
  Fetch: git fetch https://git.openjdk.org/jdk8u-dev pull/121/head:pull/121

PR: https://git.openjdk.org/jdk8u-dev/pull/121