A Formal CSP Framework for Message-Passing HPC Programming

Abstract

To help programmers of high-performance computing (HPC) systems avoid communication-related errors, we employ a formal process algebra, Communicating Sequential Processes (CSP), which has a strict semantics for interprocess communication and synchronization. Verification tools are available for CSP-specified programs to prove the absence of failures such as deadlock, and to explore potential multiprocess interactions. By introducing a CSP abstraction layer on top of the popular MPI message-passing primitives, we create a framework, called CSP4MPI, designed to largely hide the complexity of parallel programming for HPC.CSP4MPI is comprised of a C++ class library that provides a CSP-based process model, and a "cookbook" of candidate solutions for HPC programmers not trained in CSP. Developers can prototype their systems using CSP, and use verification tools to examine possible points of failure before implementing via the CSP4MPI library. Alternatively, they may choose an existing, verified solution from a number of common parallel application archetypes. By using CSP4MPI, HPC developers leverage the benefits of formal specification and verification in their work, in addition to obtaining an alternate method to developing HPC applications.

The pilot approach to cluster programming in C

“…In contrast, Pilot is aimed at novice HPC programmers who could be intimidated by introducing a formal method too explicitly; however, the Pilot library approach does belong to this family. CSP4MPI [7] also aimed to help programmers avoid communication-related errors by introducing an abstraction layer over MPI. This approach was inspired by the CSP++ [8] software synthesis tool, which generates C++ from a formal CSP specification.…”

Tracking CSP computations

“…We use Λ to denote the empty chain. 9 We let Pos(t) denote the specification position of a term t. Each (parameterized) process definition N = P or N (x n ) = P of a CSP specification is labeled with specification positions. The specification position of its left-hand side is respectively Pos(N ) = (N, 0) or Pos(N (x n )) = (N (x n ), 0).…”

“…CSP has been used in research, teaching, and industry [1,4,29,42], and is nowadays applied to many different industrial problems such as medical simulations [35,20], modeling web services choreographies [34], hardware simulation and verification [38,19], cloud computing models [23], widespread concurrent languages (e.g. MPI [9], Go [53] and Verilog [48]), testing [10], and social networks modeling [24,41].…”

“…The notation "from(9,36) to(9,42)" specifies the starting and ending positions of the term in the source code, i.e., from line 9, column 36 to line 9, column 42.…”

Programming Model to Develop Supercomputer Combinatorial Solvers

“…fault-tolerance [46]), (2) Addressing specific shortcomings and development needs (e.g. reusability [47] and verifiability [48]), or (3) Providing complete solutions for specific applications (e.g. neural simulation using NEST [49]).…”