How to profile memory of a spring boot webapp running on cloud foundry?

Question

I have a Spring boot application running on internal cloud foundry space. I want to monitor the Stack and Heap memory of this web app, in order to find a StackOverflow exception originating from code.

What could be the best way to profile the application.

Answer 1

• https://content.pivotal.io/blog/new-cloud-foundry-java-buildpack-improves-developer-diagnostic-tools
• https://community.pivotal.io/s/article/How-to-Remotely-Debug-Java-Applications-on-Cloud-Foundry

1. Run your app with JMX settings

• To test profiling on your local machine run theapp with the following JMX configuration and then go to the last step "3. VisualVM configuration":

  java \
  -Dcom.sun.management.jmxremote=true \
  -Djava.rmi.server.hostname=localhost \
  -Dcom.sun.management.jmxremote.port=9999 \
  -Dcom.sun.management.jmxremote.rmi.port=9999 \
  -Dcom.sun.management.jmxremote.ssl=false \
  -Dcom.sun.management.jmxremote.authenticate=false \
  -jar theapp.jar ...
  

• To pass the JMX configuration to theapp in CF use the JBP_CONFIG_JMX environment variable (or JAVA_OPTS with params as above), manifest.yml:

  applications:
    - name: theapp
      buildpack: java_buildpack
      env:
        JBP_CONFIG_JMX: "{enabled: true, port: 9999}"
        # JAVA_OPTS: "-Dcom.sun.management.jmxremote=true -Djava.rmi.server.hostname=localhost -Dcom.sun.management.jmxremote.port=9999 -Dcom.sun.management.jmxremote.rmi.port=9999 -Dcom.sun.management.jmxremote.ssl=false -Dcom.sun.management.jmxremote.authenticate=false"
  

2. Create SSH tunnel to theapp's container

cf ssh -N -T -L 9999:localhost:9999 theapp

3. VisualVM configuration

• Download VisualVM
• Run VisualVM: visualvm --jdkhome "$JAVA_HOME"
• Add JMX connection: localhost:9999

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You can also create SSH tunnel using PuTTY

• Retrieve and display theapp's guid:

  cf app theapp --guid
  # example: 12345678-1234-1234-1234-123456789012
  

• Get a one time password for ssh clients:

  cf ssh-code
  # example: PolSkAjEzyKtrUdnA
  

• Create PuTTY SSH connection:

  • hostname: theapp.your.cloud
  • port: 2222
  • username: cf:<app-guid>/<app-instance-index>@ssh.your.cloud
    • example: cf:12345678-1234-1234-1234-123456789012/[email protected]
  • password: <ssh-code>
    • example: PolSkAjEzyKtrUdnA
  • connection/ssh/tunnels/:
    • source port: 9999
    • destination: 127.0.0.1:9999