JUNE-BUG: A Debugger for Parallel Programs on the ALEWIFE Multiprocessor

Parallel programs are more difficult to debug than sequential programs because of their increase in the complexity of interaction. Debugging is complicated both by the properties of multiprocessors in general, and by the specifics of particular multiprocessors, such as their parallelism granularity, interprocessor communication time lags, etc. Additional effort is necessary to assist users both in debugging their code and in helping them to understand it. Previous efforts have focused on either multiprocessor program debugging or program understanding; it is necessary to unify these two tasks. The tasks of program understanding and debugging are similar. By dealing with both tasks through the same program, one can create a flexible program usable both to increase program understanding and debug code. This necessarily would be a event-based tool, operating both during program execution, and during traditional debugging conditions. If successful, this would greatly contribute to increasi..