Abstract-Standard testing methods of MPI programs do not guarantee coverage of all non-deterministic interactions (e.g., wildcard-receives). Programs tested by these methods can have untested paths (bugs) that may become manifest unexpectedly. Previous formal dynamic verifiers cover the space of non-determinism but do not scale, even for small applications. We present DAMPI, the first dynamic analyzer for MPI programs that guarantees scalable coverage of the space of non-determinism through a decentralized algorithm based on Lamport-clocks. DAMPI computes alternative non-deterministic matches and enforces them in subsequent program replays. To avoid interleaving explosion, DAMPI employs heuristics to focus coverage to regions of interest. We show that DAMPI can detect deadlocks and resource-leaks in real applications. Our results on a wide range of applications using over a thousand processes, which is an order of magnitude larger than any previously reported results for MPI dynamic verification tools, demonstrate that DAMPI provides scalable, user-configurable testing coverage.

With the increasing cost of developing robust HPC software, precise data-flow analysis for MPI programs -the mainstay of HPC programming -are essential. The knowledge of communication is essential for precise data-flow analysis and the difficulty of statically determining it makes the conventional techniques insufficient. Hybrid methods combining static and dynamic techniques are needed and in this work we demonstrate one such approach in building the parallel control-flow graph which can then be used to leverage the precision of data-flow analyses for MPI programs.

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