Coverage-Driven Test Generation for Thread-Safe Classes via Parallel and Conflict Dependencies

Abstract

Thread-safe classes are common in concurrent object-oriented programs. Testing such classes is important to ensure the reliability of the concurrent programs that rely on them. Recently, researchers have proposed the automated generation of concurrent (multi-threaded) tests to expose concurrency faults in thread-safe classes (thread-safety violations). However, generating fault-revealing concurrent tests within an affordable time-budget is difficult due to the huge search space of possible concurrent tests. In this paper, we present DepCon, an approach to effectively reduce the search space of concurrent tests by means of both parallel and conflict dependency analyses. DepCon is based on the intuition that only methods that can both interleave (parallel dependent) and access the same shared memory locations (conflict dependent) can lead to thread-safety violations when concurrently executed. DepCon implements an efficient static analysis to compute the parallel and conflict dependencies among the methods of a class and uses the computed dependencies to steer the generation of tests towards concurrent tests that exhibit the computed dependencies. We evaluated DepCon by experimenting with a prototype implementation for Java programs on a set of thread-safe classes with known concurrency faults. The experimental results show that DepCon is more effective in exposing concurrency faults than state-of-the-art techniques.