As it turns out, the JVM can avoid wasting memory by compressing the object pointers or oops, so we can have the best of both worlds: allowing more than 4 GB of heap space with 32-bit references in 64-bit machines! ... To enable oop compression, we can use the -XX:+UseCompressedOops tuning flag. The oop compression is the default behavior from Java 7 onwards whenever the maximum heap size ... More on stackoverflow.com

An upcoming JEP intends to make heap sizing a thing of the past, first for ZGC, and later maybe for other collectors, too: Automatic Heap Sizing for ZGC . It didn't make JDK 25, but fingers crossed for JDK 26. More on reddit.com

You can set JVM initial and max ram percentages like so: -XX:InitialRAMPercentage=80 -XX:MaxRAMPercentage=80 Those flags cause the JVM to consume only that percentage of the pod memory, they were introduced in OpenJDK 10 [1]. This is better than setting Xmx within the docker container because it effectively lets you manage your JVM memory via the pod settings. Gives your k8s team control of actual memory usage. There were some issues with the implementation in JDK 11 which lead to OOMKilled errors (basically the flags were not respected, but that is resolved now). OOMKilled Details: https://factorhouse.io/blog/articles/corretto-memory-issues/ You still need pod level limits for those flags to take effect, but they're pretty useful. When you set your pod memory memory resources you should run with a guaranteed QoS [2] by setting both requested and limit to the same value. Guaranteed QoS means that the pod is least likely to be evicted [3]. resources: limits: memory: 8Gi requests: memory: 8Gi By the way 80% percentage is pretty high, probably safer in the general case to go with 70% cos the remaining memory will be required by the OS. Soure: I work at Factor House (and I wrote that blogpost about OOMKilled errors). We build dev tools for Apache Kafka and Apache Flink (written in Clojure, but runs on the JVM), we offer both an uberjar and a docker container that runs the uberjar as deployment methods, so we have a bit of experience tuning this stuff. [1] https://bugs.openjdk.org/browse/JDK-8146115 [2] https://kubernetes.io/docs/tasks/configure-pod-container/quality-service-pod/#create-a-pod-that-gets-assigned-a-qos-class-of-guaranteed [3] https://kubernetes.io/docs/concepts/workloads/pods/pod-qos/#guaranteed More on reddit.com

.5G os not required at all. The default is 64 MB for Off heap ( I believe you mean PermSize) for Server VMs. On newer JVMs, the MetaspaceSize ( PermSize is Metaspace) default is only 12 MB or as low as 20Mb, depending on the platform, though. Max Perm or max Metaspace sizes those are half of the physical memory but mostly never allocated. You can control this by - XX:PermSize=64M or -XX:MetaspaceSize=64M and limit -XX:MaxPermSize or -XX:MaxMetaspaceSize to let's say 128M or 256M etc. If you limit too much, the JVM won't start, though. More on reddit.com