Why Debugging Parallel Programs Needs Visualization?

The goal of debugging is location and correction of bugs in arbitrary programs to improve their reliability. Since errors are established by an application’s source code, which is in most cases implemented with some kind of textual language, the traditional focus of debugging is on textual representations. While this may be sufficient for sequential programs, it limits the usefulness of parallel debuggers when the complexity of concurrently executing and communicating processes has to be managed. A solution is offered by integrating visualization capabilities into textual debuggers. The actual need for visualization during debugging is discussed for features like placement of breakpoints, inspection of large distributed objects, and analysis of nondeterministic behavior. These examples are used to emphasize the fact, that parallel debuggers can substantially benefit from a combined textual-graphical