GEM: Graphical Explorer of MPI Programs

Formal dynamic verification can complement MPI program testing by detecting hard-to-find concurrency bugs. In previous work, we described our dynamic verifier called In-situ Partial Order (ISP) that can parsimoniously search the execution space of an MPI program while detecting important classes of bugs. One major limitation of ISP, when used by itself, is the lack of a powerful and widely usable graphical front-end. We now present a new tool called Graphical Explorer of MPI Programs (GEM) that overcomes this limitation. GEM is a plug-in architecture that greatly enhances the usability of ISP, and serves to bring ISP within reach of a wide array of programmers with its original release as part of the Eclipse Foundation´s Parallel Tools Platform (PTP) Version 3.0 in December, 2009. GEM is now a part of the PTP End-User Runtime. This paper describes GEM´s features, its architecture, and usage experience summary of the ISP/GEM combination. Recently, we applied this combination on a widely used parallel hypergraph partitioner. Even with modest amounts of computational resources, the ISP/GEM combination finished quickly and intuitively displayed a previously unknown resource leak in this code-base. Here, we also describe the process and benefits of using GEM throughout the development cycle of our own test case, an MPI implementation of the A* search. We conclude with a summary of our future plans.