Go is a programming language developed at Google, with channelbased concurrent features based on CSP. Go can detect global communication deadlocks at runtime when all threads of execution are blocked, but deadlocks in other paths of execution could be undetected. We present a new static analyser for concurrent Go code to find potential communication errors such as communication mismatch and deadlocks at compile time. Our tool extracts the communication operations as session types, which are then converted into Communicating Finite State Machines (CFSMs). Finally, we apply a recent theoretical result on choreography synthesis to generate a global graph representing the overall communication pattern of a concurrent program. If the synthesis is successful, then the program is free from communication errors.We have implemented the technique in a tool, and applied it to analyse common Go concurrency patterns and an open source application with over 700 lines of code.

The Go programming language has been heavily adopted in industry as a language that efficiently combines systems programming with concurrency. Go's concurrency primitives, inspired by process calculi such as CCS and CSP, feature channel-based communication and lightweight threads, providing a distinct means of structuring concurrent software. Despite its popularity, the Go programming ecosystem offers little to no support for guaranteeing the correctness of message-passing concurrent programs. This work proposes a practical verification framework for message passing concurrency in Go by developing a robust static analysis that infers an abstract model of a program's communication behaviour in the form of a behavioural type, a powerful process calculi typing discipline. We make use of our analysis to deploy a model and termination checking based verification of the inferred behavioural type that is suitable for a range of safety and liveness properties of Go programs, providing several improvements over existing approaches. We evaluate our framework and its implementation on publicly available real-world Go code. CCS CONCEPTS • Theory of computation → Verification by model checking; Type theory; Process calculi; • Software and its engineering → Model checking; Automated static analysis; Software verification; Concurrent programming languages;

This paper presents a framework for the static specification and safe programming of message passing protocols where the number and kinds of participants are dynamically instantiated. We develop the first theory of distributed multiparty session types (MPST) to support parameterised protocols with indexed rolesÐour framework statically infers the different kinds of participants induced by a protocol definition as role variants, and produces decoupled endpoint projections of the protocol onto each variant. This enables safe MPST-based programming of the parameterised endpoints in distributed settings: each endpoint can be implemented separately by different programmers, using different techniques (or languages). We prove the decidability of role variant inference and well-formedness checking, and the correctness of projection. We implement our theory as a toolchain for programming such role-parametric MPST protocols in Go. Our approach is to generate API families of lightweight, protocol-and variant-specific type wrappers for I/O. The APIs ensure a well-typed Go endpoint program (by native Go type checking) will perform only compliant I/O actions w.r.t. the source protocol. We leverage the abstractions of MPST to support the specification and implementation of Go applications involving multiple channels, possibly over mixed transports (e.g., Go channels, TCP), and channel passing via a unified programming interface. We evaluate the applicability and run-time performance of our generated APIs using microbenchmarks and real-world applications. CCS Concepts: • Computing methodologies → Distributed programming languages; • Software and its engineering → Source code generation; Concurrent programming languages;

International audienceA recent trend in programming language research is to use behavioral type theory to ensure various correctness properties of largescale, communication-intensive systems. Behavioral types encompass concepts such as interfaces, communication protocols, contracts, and choreography. The successful application of behavioral types requires a solid understanding of several practical aspects, from their representation in a concrete programming language, to their integration with other programming constructs such as methods and functions, to design and monitoring methodologies that take behaviors into account. This survey provides an overview of the state of the art of these aspects, which we summarize as the pragmatics of behavioral types

Abstract. This paper presents a new efficient programming toolchain for message-passing parallel algorithms which can fully ensure, for any typable programs and for any execution path, deadlock-freedom, communication safety and global progress through a static checking. The methodology is embodied as a multiparty session-based programming environment for C and its runtime libraries, which we call Session C. Programming starts from specifying a global protocol for a target parallel algorithm, using a protocol description language. From this global protocol, the projection algorithm generates endpoint protocols, based on which each endpoint C program is designed and implemented with a small number of concise session primitives. The endpoint protocol can further be refined to a more optimised protocol through subtyping for asynchronous communication, preserving original safety guarantees. The underlying theory can ensure that the complexity of the toolchain stays in polynomial time against the size of programs. We apply this framework to representative parallel algorithms with complex communication topologies. The benchmark results show that Session C performs competitively against MPI.