Database Reference
In-Depth Information
Figure9-2.JConsole showing the peak thread count for a Cassandra daemon
In this figure, you can see the two kinds of views into your application that JMX offers: the gen-
eral view about threads, memory, and CPU that every application will have, and a more detailed
view that exposes the peak thread count value. You can see that many other instrumented as-
pects of the application are also available.
NOTE
JConsole is popular because it's easy to use and ships with the JDK. But this is only one possible JMX
client. The JBoss Application Server web console, for example, is itself a JMX client of the JBoss server.
There are many aspects of an application or the JVM that can be instrumented but that may be
disabled. Thread Contention is one example of a potentially useful MBean that is turned of by
default in the JVM. These aspects can be very useful for debugging, so if you see an MBean
that you think might help you hunt down a problem, go ahead and enable it. But keep in mind
that nothing comes for free, and it's a good idea to read the JavaDoc on the MBean you want to
