The oldest tool in the JRockit Mission Control tools suite is the JRockit Management Console. The Management Console can be used to monitor the JRockit JVM and any application running in the JVM. It can also be used to alter the runtime state of certain parameters in JRockit. This chapter assumes some prior familiarity with Java Management Extensions (JMX) and the JMX terminology.
Note
For more information on JMX go to http://java.sun.com/javase/technologies/core/mntr-mgmt/javamanagement/
The Management Console relies on the JMX standard and provides a way to monitor any application that exposes manageability features through JMX, including the JRockit JVM.
In this chapter you will learn:
- How to start up the Management Console
- How to monitor and plot arbitrary MBean attributes
- How to invoke arbitrary MBean operations
- How to create trigger rules
- How to enable deadlock detection
- How to perform per-thread memory allocation and CPU profiling
- About the diagnostic commands
- How to extend the Management Console
The JRockit Management Console predates the JRockit Mission Control tools suite. It even predates JMX.
Note
The first few versions of JRockit were made available as "Virtual Machines for Java", not JVMs. The key difference is that only a virtual machine certified by Sun (now Oracle) to be compliant with the Java standard is allowed to be called a JVM. Furthermore, if the VM is not certified, it may not use the Java trademark. At that time, in order to be accepted as a Sun certified JVM, a key differentiator, known as "value add" was required. In our first attempt to become a proper Java licensee, we had specified "superior performance" as our value add. While technically true, it was not deemed to be a valid value add, so we exposed some of the online manageability aspects of the JVM instead. This is what became the JRockit Management Console.
The primary use of the Management Console is to provide detailed monitoring of one or more JRockit instances. As each monitored JVM has its own Management Console (editor), more than a few JVM instances are rarely monitored at a time. To monitor large installations for longer periods of time, a distributed solution that scales well over large amounts of JVMs should be used, such as Oracle Enterprise Manager.
The Management Console and JRockit use standard JMX technology for communication. As of Java 5.0, some aspects of using JMX to expose manageability features of the JVM are standardized through JSR-174.
Note
JSR-174 enhanced the manageability of the JVM by adding the java.lang.management classes and providing the platform MBean server.
For more information on the platform MBean server, see the Java APIs and Documentation on SDN on the Internet and search for java.lang.management.ManagementFactory.getPlatformMBeanServer()
Since the advent of JSR-174 and the platform MBean server, most Java applications and frameworks are publishing their monitoring and management MBeans to the platform MBean server, which in effect means that the Management Console can monitor most parts of the software stack running in the JVM.
As JRockit had a Management Console well before the start of JSR-174, the JRockit Management Console can also connect to pre 1.5.0 versions of JRockit. In these setups, everything still looks like JMX to the client, but underneath a proprietary protocol is used.
The rest of this chapter is dedicated to discussing the JRockit Mission Control Console and its various uses. The chapter is divided into sections corresponding to the different tabs in the Management Console, so that it can also be used as a reference to quickly check on details for a specific tab.