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Overview#

This document will demonstrate how to generate a memory dump so that you can analyze your memory usage.

Services supported#

This operation can be made in the following Java-based services:

Service JAVA_OPTIONS environment variable
auth-server CN_AUTH_JAVA_OPTIONS
casa CN_CASA_JAVA_OPTIONS
config-api CN_CONFIG_API_JAVA_OPTIONS
fido2 CN_FIDO2_JAVA_OPTIONS
link CN_LINK_JAVA_OPTIONS
saml CN_SAML_JAVA_OPTIONS
scim CN_SCIM_JAVA_OPTIONS

Steps#

Let's go through the steps needed to generate a dump in config-api:

  1. Increase the pod's memory request and limit to something larger than the default.

  2. Edit the config-api deployment and modify the JAVA_OPTIONS: 

            env:
        - name: CN_CONFIG_API_JAVA_OPTIONS
          value: -XX:MaxDirectMemorySize=400m -Xmx150m -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=/tmp -XX:MaxRAMPercentage=0

  3. Modify the command key in the deployment to add the following:

              command:
            - /bin/sh
            - -c
            - |
              /app/scripts/entrypoint.sh &
              sleep 900000000

  4. You can view the heap usage using the following command: kubectl exec -n <namespace> pod-name -- jcmd 7 GC.heap_info

  5. Now once the process meets its limit, the process should shut down without the pod getting an OOM, allowing you to get the dump from within the pod.

  6. Copy the generated dump from the pod: 

    kubectl cp -n <namespace> pod-name:tmp/java_pid7.hprof java_pid7.hprof

Last update: 2024-09-27
Created: 2024-06-04