Abstract: A software visualization tool enables a user to observe the inner workings of a computer program (e.g., a Java program) while it executes. An original program is augmented with calls to a shadow machine at locations where the original program modifies a data structure maintained by the data program or updates values in a value set maintained within the context of the data structure. A duplicate copy of the data structure and the value set for the augmented program is maintained during execution of the computer program by a shadow machine. A display engine accesses the duplicate copy of the data structure and the value set, and displays a visual representation of the duplicate copy on a display device so as to facilitate visualization of the execution of the augmented program in a dynamic and near real-time manner.