JMX with Solr

Java Management Extensions (JMX) is a technology that makes it possible for complex systems to be controlled by tools without the systems and tools having any previous knowledge of each other. In essence, it is a standard interface by which complex systems can be viewed and manipulated.

Solr, like any other good citizen of the Java universe, can be controlled via a JMX interface. Once enabled, you can use a JMX client, like jconsole, to connect with Solr.

If you are unfamiliar with JMX, you may find the following overview useful: http://docs.oracle.com/javase/8/docs/technotes/guides/management/agent.html.

Configuring JMX

If you have an existing MBean server running in Solr’s JVM, or if you start Solr with the system property -Dcom.sun.management.jmxremote, Solr will automatically identify its location on startup.

Configuring MBean Servers

An MBean server can be started at the time of Solr’s startup by passing the system parameter -Dcom.sun.management.jmxremote. See Oracle’s documentation for additional settings available to start and control an MBean server at http://docs.oracle.com/javase/8/docs/technotes/guides/management/agent.html.

Configuring a Remote Connection to Solr JMX

If you need to attach a JMX-enabled Java profiling tool, such as JConsole or VisualVM, to a remote Solr server, then you need to enable remote JMX access when starting the Solr server. Simply change the ENABLE_REMOTE_JMX_OPTS property in the solr.in.sh or solr.in.cmd (for Windows) file to true. You’ll also need to choose a port for the JMX RMI connector to bind to, such as 18983. For example, if your Solr include script sets:

ENABLE_REMOTE_JMX_OPTS=true
RMI_PORT=18983

The JMX RMI connector will allow Java profiling tools to attach to port 18983. When enabled, the following properties are passed to the JVM when starting Solr:

-Dcom.sun.management.jmxremote \
-Dcom.sun.management.jmxremote.local.only=false \
-Dcom.sun.management.jmxremote.ssl=false \
-Dcom.sun.management.jmxremote.authenticate=false \
-Dcom.sun.management.jmxremote.port=18983 \
-Dcom.sun.management.jmxremote.rmi.port=18983

We don’t recommend enabling remote JMX access in production, but it can sometimes be useful when doing performance and user-acceptance testing prior to going into production.

For more information about these settings, see: http://docs.oracle.com/javase/8/docs/technotes/guides/management/agent.html.

Making JMX connections into machines running behind NATs (e.g., Amazon’s EC2 service) is not a simple task. The java.rmi.server.hostname system property may help, but running jconsole on the server itself and using a remote desktop is often the simplest solution. See http://web.archive.org/web/20130525022506/http://jmsbrdy.com/monitoring-java-applications-running-on-ec2-i.