Package: openjdk-21-jdk Version: 21.0.8~5ea-1 openjdk is no longer "cgroup-aware" when running in a container with cgroupv2 enabled. Apparently this is a regression triggered by kernel 6.12. AFAIU openjdk relies upon some deprecated features that were dropped for the new kernel. See https://bugs.openjdk.org/browse/JDK-8347811. Sample:
% docker run -it debian:sid Unable to find image 'debian:sid' locally sid: Pulling from library/debian 6b1598688dd5: Pull complete Digest: sha256:eb835ce18611a0b66cf4b9c6a239752d8498bb528585c01a7b7141aed1097ea7 Status: Downloaded newer image for debian:sid root@b5a58a706393:/# apt update Get:1 http://deb.debian.org/debian sid InRelease [208 kB] Get:2 http://deb.debian.org/debian sid/main amd64 Packages [10.1 MB] Fetched 10.3 MB in 1s (13.0 MB/s) All packages are up to date. root@b5a58a706393:/# apt -y install default-jdk Installing: default-jdk : : root@b5a58a706393:/# grep cgroup /proc/self/mounts cgroup /sys/fs/cgroup cgroup2 ro,nosuid,nodev,noexec,relatime 0 0 root@b5a58a706393:/# uname -a Linux b5a58a706393 6.12.32-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.12.32-1 (2025-06-07) x86_64 GNU/Linux root@b5a58a706393:/# java -version openjdk version "21.0.8-ea" 2025-07-15 OpenJDK Runtime Environment (build 21.0.8-ea+5-Debian-1) OpenJDK 64-Bit Server VM (build 21.0.8-ea+5-Debian-1, mixed mode, sharing) root@b5a58a706393:/# java -Xlog:os+container=trace --version [0.001s][trace][os,container] OSContainer::init: Initializing Container Support [0.001s][debug][os,container] Detected optional pids controller entry in /proc/cgroups [0.001s][debug][os,container] controller cpuset is not enabled [0.001s][debug][os,container] controller memory is not enabled [0.001s][debug][os,container] One or more required controllers disabled at kernel level. openjdk 21.0.8-ea 2025-07-15 OpenJDK Runtime Environment (build 21.0.8-ea+5-Debian-1) OpenJDK 64-Bit Server VM (build 21.0.8-ea+5-Debian-1, mixed mode, sharing) This is not OK. In a sid container running on Bookworm (kernel 6.1.140) you get the expected result: root@6e5d48c668e9:/# grep cgroup /proc/self/mounts cgroup /sys/fs/cgroup cgroup2 ro,nosuid,nodev,noexec,relatime,nsdelegate,memory_recursiveprot 0 0 root@6e5d48c668e9:/# uname -a Linux 6e5d48c668e9 6.1.0-32-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.1.129-1 (2025-03-06) x86_64 GNU/Linux root@6e5d48c668e9:/# java -version openjdk version "21.0.8-ea" 2025-07-15 OpenJDK Runtime Environment (build 21.0.8-ea+5-Debian-1) OpenJDK 64-Bit Server VM (build 21.0.8-ea+5-Debian-1, mixed mode, sharing) root@6e5d48c668e9:/# java -Xlog:os+container=trace --version [0.001s][trace][os,container] OSContainer::init: Initializing Container Support [0.001s][debug][os,container] Detected optional cpuset controller entry in /proc/cgroups [0.001s][debug][os,container] Detected optional pids controller entry in /proc/cgroups [0.001s][debug][os,container] Detected cgroups v2 unified hierarchy [0.001s][trace][os,container] Path to /cpu.max is /sys/fs/cgroup/cpu.max [0.001s][trace][os,container] Raw value for CPU quota is: max [0.002s][trace][os,container] CPU Quota is: -1 [0.002s][trace][os,container] Path to /cpu.max is /sys/fs/cgroup/cpu.max [0.002s][trace][os,container] CPU Period is: 100000 [0.002s][trace][os,container] OSContainer::active_processor_count: 8 [0.002s][trace][os,container] CgroupSubsystem::active_processor_count (cached): 8 [0.002s][trace][os,container] total physical memory: 16669937664 [0.002s][trace][os,container] Path to /memory.max is /sys/fs/cgroup/memory.max [0.002s][trace][os,container] Raw value for memory limit is: max [0.002s][trace][os,container] Memory Limit is: Unlimited [0.002s][debug][os,container] container memory limit unlimited: -1, using host value 16669937664 [0.003s][trace][os,container] CgroupSubsystem::active_processor_count (cached): 8 [0.026s][trace][os,container] Path to /cpu.max is /sys/fs/cgroup/cpu.max [0.026s][trace][os,container] Raw value for CPU quota is: max [0.026s][trace][os,container] CPU Quota is: -1 [0.026s][trace][os,container] Path to /cpu.max is /sys/fs/cgroup/cpu.max [0.026s][trace][os,container] CPU Period is: 100000 [0.026s][trace][os,container] OSContainer::active_processor_count: 8 openjdk 21.0.8-ea 2025-07-15 OpenJDK Runtime Environment (build 21.0.8-ea+5-Debian-1) OpenJDK 64-Bit Server VM (build 21.0.8-ea+5-Debian-1, mixed mode, sharing) Regards Harri
