RFR: JDK-8287011: Container information could be improved [v2]

[Severin Gehwolf]

On Thu, 2 Jun 2022 14:18:12 GMT, Matthias Baesken <mbaesken at openjdk.org> wrote:

>> The change adds some potentially interesting cgroup v1 and v2 metrics to hs_err / hs_info files.
>
> Matthias Baesken has updated the pull request incrementally with one additional commit since the last revision:
> 
>   adjust output in os_linux.cpp

A couple of comments:
- This introduces a couple of version specific info which is stubbed on the versions that don't support them. It's in conflict with the design of OSContainer to only contain metrics which are commonly supported (should do the same on all versions). On the JDK side those version specific metrics live in version specific classes. Not sure if this design applies well to hotspot code.
- This is untested code. If anything, please add tests for this to `TestMisc.java` which uses PrintContainerInfo to exercise this code.
- What's the use-case for those diagnostics? Usually on kubernetes swap is disabled so the swap info there is quite useless in that case. Why is the kernel memory info needed? The bug doesn't say *why* it's important to have.

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PR: https://git.openjdk.java.net/jdk/pull/8991