Java VisualVM – Developer`s Nightmare is Over
http://www.taranfx.com/blog/java-visualvm

Sun now integrates a profiler in the jdk

Java VisualVM – Developer`s Nightmare is Over

VisualVM is an open source tool for monitoring and profiling your Java applications. VisualVM is now integrated with JDK 6 update 7 release and also available as a stand-alone setup. Java 7 plans to integrate next version 1.2.