Static deadlock detection for concurrent go by global session graph synthesis

Abstract

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.

Bounded verification of message-passing concurrency in Go using Promela and Spin

“…Virtual method calls (on interfaces) are particularly difficult to model. As in [7,8,10,12,14], we do not support channel passing (since we abstract away the data sent over channels). We note that our empirical survey [3] found that only 6% of projects used channels that carry channels.…”

“…Also, Zaks and Joshi [19] use Spin to verify multi-threaded C programs using their LLVM representation and custom virtual machine. Several works focus on the verification of message-passing concurrency in Go [7,8,10,12,14,15,16]. Four papers studied static verification using behavioural models.…”

“…Note that this program spawns |files| threads and creates a channel whose capacity is |files|. The length of files is unknown at compile-time, hence this program cannot be checked for concurrency errors with existing static verification techniques for Go [7,8,10,12,14].…”

Benefits of session types for software development

“…Programming with session types can be understood and used efficiently by real world programmers. All papers extending various programming languages [17,3,11,9,13,16] assume that this is the case. However, session types add another layer of complexity to programming.…”

“…They have proved popular, finding their way into various programming languages and tools. As of late there has been an emphasis on implementations, be that in existing languages: C [17], Erlang [3], Go [16], Java [11,9], to name just a few, or in new languages: Scribble, Links [13], SILL. The session type community certainly believes it to be worthwhile to add session types to as many languages as possible.…”