RFR: 8269851: OperatingSystemMXBean getProcessCpuLoad reports incorrect process cpu usage in containers [v7]

[Severin Gehwolf]

On Tue, 13 Jul 2021 05:19:25 GMT, xpbob <github.com+7837910+xpbob at openjdk.org> wrote:

>> …ocess cpu usage in containers
>
> xpbob has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Set 1.0 for cpu set max

Except for the missing comments in the new code blocks this looks good to me.

src/jdk.management/unix/classes/com/sun/management/internal/OperatingSystemImpl.java line 98:

> 96:                 hostTicks = hostTicks * containerCPUs / totalCPUs;
> 97:                 return getUsageDividesTotal(cpuUsageSupplier().getAsLong(), hostTicks);
> 98:             } else {

The old code had these comments here. We should add them as they're still relevant:


                // If CPU quotas and shares are not active then find the average system load for
                // all online CPUs that are allowed to run this container.

                // If the cpuset is the same as the host's one there is no need to iterate over each CPU

src/jdk.management/unix/classes/com/sun/management/internal/OperatingSystemImpl.java line 106:

> 104:                         cpuSet = containerMetrics.getCpuSetCpus();
> 105:                     }
> 106:                     if (cpuSet == null) {

Please add the comment as it was in the original code:


                        // cgroups is mounted, but CPU resource is not limited.
                        // We can assume the VM is run on the host CPUs.

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Marked as reviewed by sgehwolf (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/4702