[11u] RFR: 8226575: OperatingSystemMXBean should be made container aware

[Severin Gehwolf]

Hi,

Could I please get a review of this container awareness backport for
OperatingSystemMXBean? I'd like to backport this since 8u will soon
receive a similar update and this would avoid regressions when
upgrading from JDK 8 to JDK 11 in the future.

The JDK 14 patch doesn't exactly apply since for an 11u backport it's
not appropriate to add new methods in OperatingSystemMXBean. Thus, for
this backport the old methods now return container aware values on an
OS which supports them (i.e. Linux only). I'm going to propse a test
fix, JDK-8236617, as a follow-up.

webrev: http://cr.openjdk.java.net/~sgehwolf/webrevs/JDK-8226575/jdk11/02/webrev/
Bug: https://bugs.openjdk.java.net/browse/JDK-8226575
Corresponding CSR: https://bugs.openjdk.java.net/browse/JDK-8248804 (approved)

Testing: tier 1, :jdk_management, docker tests on Linux x86_64. All pass.

Thoughts?

Thanks,
Severin