JACOT: a tool to dynamically visualise the execution of concurrent Java programs

The introduction of concurrency within emerging languages such as Java brings challenging new concepts to the user. Owing to the inherent non-determinism of threads and multiple flow of control in concurrent programs, traditional debugging and comprehension techniques, such as source code analysis, do not suffice. We believe that visualisation can assist in expediting comprehension of concurrent programs. We present, Jacot, a visualisation tool to depict the execution of concurrent Java programs. Jacot has two views based on the Unified Modeling Language (UML) Sequence diagram paradigm. It is implemented in Java and uses the Java Debug Interface (JDI) for event gathering. It depicts the interaction between objects and the interleaving of threads in a timely fashion, using method invocations.