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The Oracle JDK distributes two major tools for monitoring and profiling java applications or more accurately the Java Virtual Machine (JVM).
The JConsole graphical user interface is a monitoring tool that complies to the Java Management Extensions (JMX) specification. JConsole uses the extensive instrumentation of the Java Virtual Machine (Java VM) to provide information about the performance and resource consumption of applications running on the Java platform.
http://docs.oracle.com/javase/7/docs/technotes/guides/management/jconsole.html
VisualVM is a visual tool integrating several commandline JDK tools and lightweight profiling capabilities. Designed for both production and development time use, it further enhances the capability of monitoring and performance analysis for the Java SE platform.</blockquote>
http://visualvm.java.net/ 
