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15 lines
1.3 KiB
Markdown
15 lines
1.3 KiB
Markdown
# JMX Monitoring
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Java offers Java Management Extensions (JMX) which is built into the JDK since Java 6. We can use this to monitor the state of a live server VM without the need to attach a debugger or profiler and can thus gain at least some high-level insights into the VM's health status.
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Our first JMX MXBean is `com.sap.sailing.server.RacingEventServiceMXBean` for which an instance is created and registered by the `com.sap.sailing.server.impl.Activator` and which reads properties from the `RacingEventService` instance. This can also be used as an example for further MXBeans that make other aspects of our server manageable and monitorable in the console.
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In order to gain access to the VM using JMX it needs to be started with a few system properties set:
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<pre>
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-Dcom.sun.management.jmxremote
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</pre>
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You can then launch your local `jconsole` tool from the JDK to connect to the remote VM. Ideally, you launch a VNC server on the machine running the Java VM that you want to monitor and execute `jconsole` in a terminal running in that VNC server. This avoids firewall hassle which can be pretty difficult to handle when trying to monitor a JMX-enabled VM remotely.
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<center>Screenshot of a VNC viewer showing the running JConsole client.</center> |