ISP: a tool for model checking MPI programs

TL;DR: This paper presents a tool called ISP (in-situ partial order) which aspires to grow into a practical MPI model checker.

Abstract: A significant body of parallel programs are written using MPI [1]. Bugs in MPI programs arise due to many reasons, for example: (i) during manual optimizations that turn blocking sends/receives into their non-blocking counterparts, (ii) in the context of using wild-card communications (and the resulting non-determinism), and (iii) in programs that use one-sided communication [2]. Programmers are acutely aware of the need to test parallel programs over all their interleavings. They also known that this is impossible, thus confining testing to interleavings that are guessed to be adequate – very often incorrectly, as it turns out. Model checking [4] has helped debug many concurrent systems by relying on an exhaustive search of all possible interleavings – albeit on a suitably abstracted system model. For example, SPIN [5] recently won ACM’s prestigious software award, and has been used to verify many real-world protocols. For model checking to be successful in practice: (i) Designers must have modestly expensive techniques to create models of the protocols to be verified. (ii) They must be able to examine a fraction of the interleavings in a concurrent system, and be able to claim that the remaining interleavings are equivalent and hence need not be examined, using a suitable state space reduction algorithm [4, 5]. This paper presents a tool called ISP (in-situ partial order) which aspires to grow into a practical MPI model checker. In the only other active research effort on developing a model checker (called MPI SPIN) for MPI programs [6], the following approach is taken: (i) they model MPI library functions in Promela (SPIN’s modeling language), and uses SPIN for verification; (ii) they use the C extension features of SPIN to model advanced features such as non-blocking communication commands. (iii) they require users to manually express their intended MPI C program in MPI SPIN