** Package changed: linux-meta-hwe-6.14 (Ubuntu) => openjdk-21 (Ubuntu)
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https://bugs.launchpad.net/bugs/2117446
Title:
6.14.0 (24.04 HWE) breaks Java heap ergonomics in container
Status in openjdk-21 package in Ubuntu:
New
Bug description:
Given this `Vagrantfile`
```
Vagrant.configure("2") do |config|
config.vm.box = "boxen/ubuntu-24.04"
config.vm.box_version = "2025.04.02.21"
config.vm.provider "virtualbox" do |vb|
vb.memory = "4096"
end
end
```
run `vagrant up` and when ready, `vagrant ssh`. Now install Docker as
per https://docs.docker.com/engine/install/ubuntu/ and also `sudo
usermod -aG docker $USER` and `sudo apt dist-upgrade` and then log
out, `vagrant halt`, `vagrant up`, `vagrant ssh` again to log back in
with the freshest 6.8.0 (general) kernel and running in the `docker`
group. Run
```
docker run -m 1GB eclipse-temurin java -XshowSettings:vm
-XX:MaxRAMPercentage=50 -version
```
You should see something like
```
Max. Heap Size (Estimated): 494.94M
```
i.e., ½ of 1Gb ~ 500m, as expected.
Now
```
sudo apt-get install --install-recommends linux-generic-hwe-24.04
```
and reboot, so as to be running 6.14.0. Run the Docker/Java command
again and you will get
```
Max. Heap Size (Estimated): 1.90G
```
which is incorrect: the heap size is being taken from the physical RAM
of the VM, not the resources allocated to the container.
----
Originally observed in my 24.04.2 desktop machine, when running
https://github.com/kubernetes-sigs/kind and specifying pods with
specific memory limits which run Java without an explicit heap size (a
common setup which ensures the JVM will take good advantage of
whatever container limits you offer it). Until a few days ago, this
worked fine; on 2025-07-18 I apparently accepted a kernel upgrade to
6.14.0 from 6.8.0, and now these pods frequently crash with
`OOMKilled` status unless I manually set an explicit heap size smaller
than the container limit, such as with `-Xmx2g`. Can be seen using
Kind (0.29.0) though the setup is more complex than with Docker:
```
kubectl run --restart=Never --rm -ti --image eclipse-temurin
--overrides='[{"op":"replace", "path":"/spec/containers/0/resources/limits",
"value":{"memory": "2048Mi"}}]' --override-type=json java$RANDOM -- java
-XshowSettings:vm -version | fgrep -i heap
```
now prints
```
Max. Heap Size (Estimated): 15.62G
```
which seems to be taking ¼ of my 64Gb physical RAM, whereas running
the same command against GKE (1.32) in the cloud
```
Max. Heap Size (Estimated): 512.00M
```
as expected.
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