Kieker is a framework for continuous monitoring and dynamic analysis of distributed software systems. Being designed for continuous operation, it induces only a low overhead. The TraceAnalysis tool allows to analyze and visualize trace information.
JRET (Java Reverse-Engineering Tool) is a program that is capable of reconstructing sequence diagrams from JUnit testsuites through dynamic analysis. It is written in Java/AspectJ and provides a GUI as well as command-line possibilities.