JVM and Kubernetes walk into the bar...

on YouTube ↗50m

" summary

Shows how Kubernetes resource requests and limits map to Linux cgroups and how modern JVMs read those cgroup values: memory limits from cgroups become the JVM max heap basis (default maxHeapPercent 25%) and exceeding that can cause OOM kills. Demonstrates with live-created pods, docker/container inspect output, kubectl, and java -XX flags, and reproduces a CPU-count bug where giving 500 millicores without a CPU limit made Java 17.0.4 see only one CPU (fixed in 17.0.6).

AI-written summary · about

" chapters (7)

1. 0:00Introduction
2. 4:39What is a container
3. 14:19Kubernetes resource management
4. 27:10JVM in containers
5. 38:38Java memory and CPU
6. 46:07Best practices and pitfalls
7. 49:16Summary and Q&A

" related talks

• 47mCPU & Memory, Requests & Limits, QoS & CFS: The JVM in the Kubernetes PodHalil Cem Gürsoy · JCON Europe 2023
• 05mtalks toMohammed Aboullaite, Mark Hazell · Devoxx Belgium 2019
• 50mWhy you’re going to FAIL running Java on docker!Burr Sutter · JavaDay Ukraine 2017
• 42mContainers & Java: What I wish I have been told!Mohammed Aboullaite · Devoxx Belgium 2019
• 58mContainer Friendly Java 9Ken Sipe · Developer Summit 2020
• 48mJava in Containers - Part DeuxDavid Delabassee · Developer Summit 2020
• 45mCatching the 137-Killer: A Java Memory Forensics InvestigationMartijn Dashorst · Voxxed Days Ticino 2026
• 35mNO ONE PUTS Java IN THE CONTAINERJörg Schad · Codemotion Milan 2017