Verifying Concurrent Programs Using Contracts

The central notion of this paper is that of contracts for concurrency, allowing one to capture the expected atomicity of sequences of method or service calls in a concurrent program. The contracts may be either extracted automatically from the source code, or provided by developers of libraries or software modules to reflect their expected usage in a concurrent setting. We start by extending the so-far considered notion of contracts for concurrency in several ways, improving their expressiveness and enhancing their applicability in practice. Then, we propose two complementary analyses—a static and a dynamic one—to verify programs against the extended contracts. We have implemented both approaches and present promising experimental results from their application on various programs, including real-world ones where our approach unveiled previously unknown errors.