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Profile an Application Running on SapMachine with JFR/JMC

You can use Java Flight Recorder (JFR) to profile your Java application on SapMachine, and Java Mission Control (JMC) to do remote profiling and analysis.

Prerequisites

  • You have downloaded and installed a JDK Mission Control console. To do that, go to SapMachine → Download → JMC 9, select your operating system, and then choose Download.

  • You have installed the Cloud Foundry command line interface. See: Download and Install the cf CLI

  • You are logged on to a SAP BTP, Cloud Foundry space. See: Log On to the Cloud Foundry Environment Using cf CLI

  • The version of your buildpack is at least 1.110.0 (for SAP Java Buildpack 1) or 2.24.0 (for SAP Java Buildpack 2).

  • The version of your SapMachine is at least 17.0.14 or 21.0.6.

  • You have a Java application that is up and running on SAP BTP, Cloud Foundry.

  • You have enabled SSH for your application. See: Configuring SSH access at the app level

Context

The commands below use async-profiler, which is a lightweight command-line tool that uses low memory resources. You can use it to execute jcmd commands without worrying about high memory consumption or potential Out-Of-Memory errors during profiling. The async-profiler tool is integrated in SapMachine, thus no need to download it.

To profile with JMC, you need to start the Management Agent on a RMI port and then open an SSH tunnel to connect to that port.

Note:

In the steps below, we use myapp and 5555 as exemplary application name and port. Replace them with your actual app name and a free port number on your localhost.

Procedure

  1. Set the RMI server to localhost. To do that, set the following JBP_CONFIG_JAVA_OPTS option in the manifest.yml file of your application:

    
---
applications:
- name: myapp
  buildpack: sap_java_buildpack_jakarta
...
  env:
    TARGET_RUNTIME: tomcat
    JBP_CONFIG_COMPONENTS: "jres: ['com.sap.xs.java.buildpack.jre.SAPMachineJRE']"
    JBP_CONFIG_SAP_MACHINE_JRE: '{version: 21.+}'
    JBP_CONFIG_JAVA_OPTS: "[java_opts: '-Djava.rmi.server.hostname=127.0.0.1']"

  2. Start the Management Agent by running jcmd in your Cloud Foundry container. Execute:

    cf ssh myapp -c "app/META-INF/.sap_java_buildpack/sap_machine_jre/bin/asprof jcmd $(pgrep java) ManagementAgent.start jmxremote.authenticate=false jmxremote.ssl=false jmxremote.port=5555 jmxremote.rmi.port=5555"

    Depending on what your SapMachine is using (JRE or JDK), specify the path accordingly (sap_machine_jre or sap_machine_jdk). To learn more, see: SapMachine

    Result:

    
7:
Command executed successfully

    Management Agent is started and is listening to port 5555.

  3. (Optional) You can check the status of the Management Agent. Execute:

    cf ssh myapp -c "app/META-INF/.sap_java_buildpack/sap_machine_jre/bin/asprof jcmd $(pgrep java) ManagementAgent.status"

  4. Enable an SSH tunnel for this port. Execute:

    cf ssh myapp -N -T -L 5555:127.0.0.1:5555

    Your local port 5555 is connected to the remote port 5555 of the JVM, which is running in the Cloud Foundry container.

    Note:

    The connection is active until you close the SSH tunnel. When you finish profiling, close the SSH tunnel by pressing [Ctrl] + [C].

  5. Connect with JMC to localhost:5555. To do that:

    1. Open your JDK Mission Control (JMC) console.

    2. From, the JVM Browser tab, choose icon Create a new custom JVM connection.

    3. For Port, enter 5555 (or your actual port number), and then choose Finish.

  6. In the left-side menu, a new node localhost:5555 appears.

  7. Double-click on MBean Server.

  8. To start profiling, go to Flight Recorder and from its context menu, choose Start Flight Recording.

  9. Set up the event settings. From the drop-down menu, choose one of the following options (templates):

    • Continuous – Low overhead configuration, safe for continuous use in production environments

    • Profiling – Low overhead configuration for profiling

    • gc – GC related events. Generates a small recording size.

    • gc_details – GC related events. Gets heap statistic and generates a large recording size.

    • Create your own configuration. To do that, choose Template Manager, then select a predefined template and choose Duplicate. Rename the new template and edit its configuration parameters according to your needs and preferences.

  10. After profiling is done, go to localhost:5555 and from its context menu, choose Disconnect.

  11. Then go back to your command line and close the SSH tunnel by pressing [Ctrl] + [C].

  12. Stop the Management Agent. Execute:

    cf ssh myapp -c "app/META-INF/.sap_java_buildpack/sap_machine_jre/bin/asprof jcmd $(pgrep java) ManagementAgent.stop"