[jdk21u-dev] RFR: 8349988: Change cgroup version detection logic to not depend on /proc/cgroups

[duke]

On Fri, 24 Oct 2025 14:55:29 GMT, Sergey Chernyshev <schernyshev at openjdk.org> wrote:

> Hi all,
> 
> This is a clean backport of JDK-8349988 to JDK 21. The only minor context conflict is in src/hotspot/share/prims/whitebox.hpp.
> 
> The change improves container detection with newer kernels such as 6.14 HWE ([bug](https://bugs.launchpad.net/ubuntu/+source/linux-hwe-6.14/+bug/2122368)).
> 
> 
> podman run -v $TEST_JDK:/opt/jdk --rm -ti --memory 200m --memory-swap 200m ubuntu:24.04 /opt/jdk/bin/java -XshowSettings:system --version
> 
> 
> 
> --- before	2025-10-24 16:33:52.000000000 +0200
> +++ after	2025-10-24 16:34:19.000000000 +0200
> @@ -1,6 +1,18 @@
>  Operating System Metrics:
>      Provider: cgroupv2
> -    System not containerized.
> +    Effective CPU Count: 12
> +    CPU Period: 100000us
> +    CPU Quota: -1
> +    CPU Shares: -1
> +    List of Processors: N/A
> +    List of Effective Processors: N/A
> +    List of Memory Nodes: N/A
> +    List of Available Memory Nodes: N/A
> +    Memory Limit: 200.00M
> +    Memory Soft Limit: 0.00K
> +    Memory & Swap Limit: 200.00M
> +    Maximum Processes Limit: 2048
> +
>  openjdk 21.0.10-internal 2026-01-20
>  OpenJDK Runtime Environment (build 21.0.10-internal-adhoc.user.jdk21u)
>  OpenJDK 64-Bit Server VM (build 21.0.10-internal-adhoc.user.jdk21u, mixed mode, sharing)
> 
> 
> 
> Tests:
> 
> No regressions observed in `test/hotspot/jtreg/containers/`, `test/jdk/jdk/internal/platform`
> 
> Details:
> 
> <details><summary>kernel 6.14 HWE Cgroup v2</summary>
> <p>
> 
> 
> --- test_results/summaryHotspotOrigCgv2.txt	2025-10-23 18:52:12.000000000 +0200
> +++ test_results/summaryHotspotUpdatedCgv2.txt	2025-10-23 18:52:12.000000000 +0200
> @@ -2,18 +2,18 @@
>  containers/cgroup/TestContainerized.java            Passed. Execution successful
>  containers/docker/DockerBasicTest.java              Passed. Execution successful
>  containers/docker/ShareTmpDir.java                  Passed. Execution successful
> -containers/docker/TestCPUAwareness.java             Failed. Execution failed: `main' threw exception: java.lang.RuntimeException: 'active_processor_count.*1' missing from stdout/stderr
> -containers/docker/TestCPUSets.java                  Failed. Execution failed: `main' threw exception: java.lang.RuntimeException: assertTrue: expected true, was false
> -containers/docker/TestContainerInfo.java            Passed. Skipped: jtreg.SkippedException: This test is cgroups v2 specific, skipped on cgroups v1
> -containers/docker/TestJFREvents.java                Failed. Execution failed: `main' threw exception: java.lang.RuntimeException: 'totalSize = 209715200' missing from stdout/stderr
> +containers/docker/Tes...

@sercher 
Your change (at version 0275d345d754ee83bb503064c450841ebac65730) is now ready to be sponsored by a Committer.

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PR Comment: https://git.openjdk.org/jdk21u-dev/pull/2390#issuecomment-3469667615