[8u] RFR: 8269851: OperatingSystemMXBean getProcessCpuLoad reports incorrect process cpu usage in containers

[Andrew Hughes]

On 19:31 Mon 23 Aug     , Severin Gehwolf wrote:
> Hi,
> 
> Please review this OpenJDK 8u backport of 8269851 which fixes an issue
> of process CPU load calculation of the OS MXBean when run with CPU
> limits in a container. Please see the bug how this manifests. The
> OpenJDK 11u patch doesn't apply cleanly since getProcessCpu0() isn't in
> 8u (introduced with JDK-8022323; non-public) and some context
> differences.
> 
> Part of this backport moves previously native getProcessCpuLoad() ->
> getProcessCpuLoad0() and makes it private. Otherwise the patch is the
> same as the JDK 11u variant.
> 
> Bug: https://bugs.openjdk.java.net/browse/JDK-8269851
> webrev: https://cr.openjdk.java.net/~sgehwolf/webrevs/JDK-8269851/jdk8/01/webrev/
> 
> Testing: Builds on AIX, Solaris, Linux, Windows, Mac. Manual tests on
> Linux x86_64 using the reproducer.
> 
> Thoughts?
> 
> Thanks,
> Severin
> 

I think we should bring in JDK-8022323 first. 8226575 already brought
in a lot of the renamings on the UNIX side only, and it seems we'll be
continually cherry-picking parts of 8022323 if changes are needed to
the remaining functions. As it stands, the native functions are a bit
of a mess of public and private functions, and at a mismatch with the
Windows side.

Plus, the fact that the bug description - "[JavaSecurityScanner]
review package com.sun.management.* Native methods should be private"
- suggests these changes were made due to some security scan makes me
think this is a good thing to backport in its own right.

I'll post the backport in its own thread. The Windows side was
completely clean, and the changes on the UNIX side were only needed
due to skipping the changes already made by 8226575.

With that in, this change should be pretty close to the 11u one.

Thanks,
-- 
Andrew :)

Senior Free Java Software Engineer
Red Hat, Inc. (http://www.redhat.com)

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