I use YourKit Java Profiler to support my work on the Apache Tomcat project. I have been using the tool for several years and continue to be impressed by the ease of use and available functionality.
In the past I have used the tool to identify memory leaks and then confirm the leaks have been resolved. More recently, the CPU profiler quickly identified the root cause of a performance and potential DOS issue.
I would recommend YourKit Java Profiler to anyone looking for an easy to use, highly functional profiling tool.
Mark Thomas
[i]Please note that the views expressed are my own and not those of the Apache Software Foundation.[/i]