Java in a Container
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External
- https://developers.redhat.com/blog/2017/03/14/java-inside-docker/
- https://blog.softwaremill.com/docker-support-in-new-java-8-finally-fd595df0ca54
- https://stackoverflow.com/questions/54292282/clarification-of-meaning-new-jvm-memory-parameters-initialrampercentage-and-minr/54297753#54297753
Internal
- Docker Container Best Practices
- Java Memory
- Kubernetes Resources Management Concepts
- Docker Resources Management Concepts
Overview
When running java in a container, the max heap should always be explicitly set with -Xmx, based on the application needs and the container limits.
Java max heap limit can also be calculated based on the container limits.
Generic script that correlates JVM memory settings to the container limits: https://github.com/fabric8io-images/run-java-sh, https://github.com/fabric8io-images/run-java-sh/blob/master/fish-pepper/run-java-sh/fp-files/run-java.sh.
Let JVM Adjust Memory Relative to CGroups Limits
Experimental Options
Java 1.8.0_181
java -XX:+UnlockExperimentalVMOptions -XX:+UseCGroupMemoryLimitForHeap -XX:+PrintFlagsFinal -version | | grep MaxHeapSize
Java 1.8.0_221
java -XX:MaxRAMPercentage=20.0 -XX:+PrintFlagsFinal -version | grep MaxHeapSize
Other flags:
-XX:InitialRAMPercentage
-XX:MinRAMPercentage