RFR: 8264482: container info misleads on non-container environment

[Severin Gehwolf]

On Wed, 31 Mar 2021 06:24:06 GMT, Yasumasa Suenaga <ysuenaga at openjdk.org> wrote:

> hs_err log and `VM.info` dcmd shows cgroup information as container information even though the process run on non-container environment as following.
> 
> container (cgroup) information:
> container_type: cgroupv2
> cpu_cpuset_cpus: not supported
> cpu_memory_nodes: not supported
> active_processor_count: 4
> cpu_quota: not supported
> cpu_period: not supported
> cpu_shares: not supported
> memory_limit_in_bytes: unlimited
> memory_and_swap_limit_in_bytes: unlimited
> memory_soft_limit_in_bytes: unlimited
> memory_usage_in_bytes: 164163584
> memory_max_usage_in_bytes: not supported
> 
> We can use cgroup outside of container, so it is useful to show. However cgroup is different from container. We should distinguish them.
> And also it is useful if we can see container runtime in this section. So I added it. We can see following contents in this section after this change.
> 
> cgroup information:
> cgroup_type: cgroupv2
> container runtime: podman
> cpu_cpuset_cpus: not supported
> cpu_memory_nodes: not supported
> active_processor_count: 4
> cpu_quota: not supported
> cpu_period: not supported
> cpu_shares: not supported
> memory_limit_in_bytes: unlimited
> memory_and_swap_limit_in_bytes: unlimited
> memory_soft_limit_in_bytes: unlimited
> memory_usage_in_bytes: 256176128
> memory_max_usage_in_bytes: not supported
> 
> In case of systemd, it checks PID (PID 1 or not) and `$container` in PID 1. We should check them to know the JVM runs on the container or not.
> 
> https://github.com/systemd/systemd/blob/68337e55f62cf49b7bdfb73dc5662e23b0ea17fa/src/basic/virt.c#L619

I'm a bit nervous about the container_runtime addition. Can this be done in a separate bug, please? What testing has been done? Has this been tested with docker and podman? Did you run tests in `test/hotspot/jtreg/containers` ?

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PR: https://git.openjdk.java.net/jdk/pull/3280