K
Q

Set Xmx and Xms for java application running on k8s

12/7/2021

I've an application running on k8s and would like to updated the java heapsize . I've updated the JAVA_OPTS environnement variable and set it in the deployment file as below

- name: JAVA_OPTS
              value: "-Xmx768m -XX:MaxMetaspaceSize=256m"

but when i run the below command it looks like my changes does not takes effect 

 java -XX:+PrintFlagsFinal -version | grep -iE 'HeapSize|PermSize|ThreadStackSize'
     intx CompilerThreadStackSize                   = 0                                   {pd product}
    uintx ErgoHeapSizeLimit                         = 0                                   {product}
    uintx HeapSizePerGCThread                       = 87241520                            {product}
    uintx InitialHeapSize                          := 33554432                            {product}
    uintx LargePageHeapSizeThreshold                = 134217728                           {product}
    uintx MaxHeapSize                              := 536870912                           {product}
     intx ThreadStackSize                           = 1024                                {pd product}
     intx VMThreadStackSize                         = 1024                                {pd product}
openjdk version "1.8.0_212"
OpenJDK Runtime Environment (IcedTea 3.12.0) (Alpine 8.212.04-r0)
OpenJDK 64-Bit Server VM (build 25.212-b04, mixed mode)

I'm i wrong can someone help me and explain how to set hose values ?

-- bilel
java
kubernetes

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2 Answers

12/7/2021

You can use command and args under the containers section for this. for example:

      containers:
      - name: test
        image: test:latest
        command: ["java"]
        args: ["-Xms256m","-Xmx768m","-jar","/app.jar"]
-- Hamid Ostadvali
Source: StackOverflow
12/8/2021

I see that you used OpenJDK Alpine to deploy a JAVA application, so you need to use this environment "JAVA_TOOL_OPTIONS" instead of "JAVA_OPTS", something like:

spec:
  containers:
  - name: jvm_options
    image: xxx:xxx
    env:
    - name: JAVA_TOOL_OPTIONS
      value: "-Xmx768m -XX:MaxMetaspaceSize=256m"

Once your application is running, you can check the application log and you will find the log below:

Picked up JAVA_TOOL_OPTIONS: -Xmx768m -XX:MaxMetaspaceSize=256m
-- Vincent Chan
Source: StackOverflow