Static-analysis Assisted Dynamic Verification to Efficiently Handle Waitany Non-determinism

We consider the problem of verifying MPI using MPI_Waitany (and related operations wait/test some/all). Such programs have a higher degree of non-determinism over which user-written test harnesses cannot exert adequate control. This makes conventional MPI program testing even more ineffective. Our previous work has demonstrated the advantages of an MPI-specific dynamic partial order reduction algorithm called POE in a tool called ISP in dramatically reducing the number of interleavings during formal dynamic verification. We show that POE can become ineffective when näıvely applied to MPI programs with MPI_Waitanys. As a novel solution, we employ static analysis in a supporting role to POE to determine the extent to which the out parameters of MPI_Waitany can affect subsequent control flow statements. This informs ISP’s scheduler to exert even more intelligent backtrack/replay control. Our results indicate that this combined use of static analysis and POE can lead to exponentially better overall verification time.