Industries incorporated ~ GCViewer. [enlarge] GCViewer is a free open source tool to visualize data produced by the Java VM options -verbose:gc and -Xloggc:<file>.
It also calculates garbage collection related performance metrics (throughput, accumulated pauses, longest pause, etc.). This can be very useful when tuning the garbage collection of a particular application by changing generation sizes or setting the initial heap size. See here for a useful summary of garbage collection related JVM parameters. Java Profiler - .NET Profiler - The profilers for Java and .NET. Samurai. What is "Samurai" Samurai is a tabbed GUI tail tool.
The three major things Samurai does for you are Works as a GUI based and multi tabbed "tail -f"Picks up thread dumps from std/stderr output and visualize them.Visualizes "-verbose:gc" logs. Java Profiler - JProfiler.