[jdk8u-dev] RFR: 8239559: Cgroups: Incorrect detection logic on some systems [v8]

[Jonathan Dowland]

> This is a backport of 53ee0c4963007b86db7979312b81f990e6ce271a via the 11u backport 53ee0c4963007b86db7979312b81f990e6ce271a for cgroups v2 support in jdk8u-dev.
> 
> It isn't clean: context differences in CgroupSubsystemFactory.java around the use of post-8u logging in the original patch.
> 
> I also had to Optional.isEmpty which is not present in 8u's Optional.

Jonathan Dowland has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains four commits:

 - Test fix by Severin. Thanks!
 - replace post-jdk8u Optional.isEmpty
 - 8239559: Cgroups: Incorrect detection logic on some systems
   
   Adjust heuristic with cgroup mounts according to mountinfo
   
   Backport-of: 53ee0c4963007b86db7979312b81f990e6ce271a
 - 8240189: [TESTBUG] Some cgroup tests are failing after JDK-8231111
   
   Reviewed-by: sgehwolf
   Backport-of: c92adf41587767e9c5c8e116cfaeb375d36928aa

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Changes: https://git.openjdk.org/jdk8u-dev/pull/136/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk8u-dev&pr=136&range=07
  Stats: 461 lines in 8 files changed: 333 ins; 49 del; 79 mod
  Patch: https://git.openjdk.org/jdk8u-dev/pull/136.diff
  Fetch: git fetch https://git.openjdk.org/jdk8u-dev pull/136/head:pull/136

PR: https://git.openjdk.org/jdk8u-dev/pull/136