Database Reference
In-Depth Information
enable in order to understand the potential impact on performance.
ThreadCPUTime
is another
example of a useful, but expensive, MBean.
Some simple values in the application are exposed as attributes. An example of this is
Thread-
ing > PeakThreadCount
, which just reports the value that the MBean has stored for the
greatest number of threads the application used at a single point in time. You can refresh to see
the most recent value, but that's pretty much all you can do with it. Because such a value is main-
tained internally in the JVM, it doesn't make sense to set it externally (it's derived from actual
events, and not configurable).
But other MBeans are configurable. They make operations available to the JMX agent that let
you get and set values. You can tell whether the MBean will let you set a value by looking at
the value for
writable
. If it's false, you will see a label indicating the read-only value; if it's
true, you will see a set of one or more fields to add your new value and a button to update it. An
example of this is the
java.util.logging.Logger
bean, as shown in .
