Abstract

. Understanding the dynamic behavior of parallel programs is a critical issue both for debugging and for optimization. A visualization tool displaying an animated sequence of the global states the program runs through offers valuable support for this process. The paper presents the features and the implementation of VISTOP, a state based visualizer for PVM applications. It supports program flow visualization based on various views and uses an event ordering algorithm to ensure consistent visualization without requiring a global clock. 1 Introduction The complex interaction of a large number of components makes programming parallel and distributed systems a complicated and error-prone task. The dynamics supported by programming libraries like PVM can make this situation even worse, because the execution of programs where tasks (or other objects) are created and deleted during runtime can be hard to comprehend. Breakpoint-based debuggers, which are also available for parallel programs n...

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