[jdk8u-dev] RFR: 8239785: Cgroups: Incorrect detection logic on old systems in hotspot [v5]

[Jonathan Dowland]

> This is a backport of add18914fb1294999877b563c734a25b4c17b922 for cgroups v2 support injdk8u-dev, via the 11u backport.
> 
> It does not apply clean:
> 
>  * context issues for changes made for the different approach for logging in 8u
>  * copyright lines
> 
> Small amount of re-working of new code that used `log_trace`/`log_debug` to use the 8u approach.

Jonathan Dowland has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 21 commits:

 - Move test to a more 8u-appropriate location
   
   Container (cgroups, docker) tests in 8u reside in
   hotspot/test/runtime/containers
 - remove duplicate include of osContainer_linux
   
   With the backport of 8189762, the include of osContainer_linux was
   moved to a later #ifdef stanza, relative to the original. This caused
   a context problem with this backport.
 - 8239785: Cgroups: Incorrect detection logic on old systems in hotspot
   
   Return NULL subsystem if no cgroup controllers are mounted.
   
   Reviewed-by: sgehwolf
   Backport-of: add18914fb1294999877b563c734a25b4c17b922
 - 8237479: 8230305 causes slowdebug build failure
   
   Declare methods as pure virtual.
   
   Backport-of: 4ca06995855b5c974321d7b3622d661b8d27ba76
 - 8253714: [cgroups v2] Soft memory limit incorrectly using memory.high
   
   The early implementation of cgroups v2 support was done with
   crun 0.8 and it contained a bug which set memory.high over
   memory.low when --memory-reservation was being used as a CLI
   option.
   
   This bug has been fixed in later crun versions, starting with
   crun 0.11. Use memory.low in OpenJDK as well.
   
   Backport-of: ff6843ca4842498791061f924c545fa9469cc1dc
 - Address style nit
 - TestCgroupSubsystemController: rework use of Files.writeString
 - CgroupSubsystemController: fix library paths
   
   We need the testlibrary copy of FileUtils but the test.lib.util copy of
   Utils (method createTempDirectory is missing from the testlib copy)
 - TestCgroupSubsystemController: fix jtreg @library path
 - Replace Arrays.compare with Arrays.equals
   
   jdk8u does not have Arrays.compare()
 - ... and 11 more: https://git.openjdk.org/jdk8u-dev/compare/198cd274...e4a44241

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

Changes: https://git.openjdk.org/jdk8u-dev/pull/135/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk8u-dev&pr=135&range=04
  Stats: 6053 lines in 40 files changed: 4148 ins; 1677 del; 228 mod
  Patch: https://git.openjdk.org/jdk8u-dev/pull/135.diff
  Fetch: git fetch https://git.openjdk.org/jdk8u-dev pull/135/head:pull/135

PR: https://git.openjdk.org/jdk8u-dev/pull/135