Testing concurrent programs using value schedules

Concurrent programs are difficult to debug and verify because of the nondeterministic nature of concurrent executions. A particular concurrency-related bug may only show up under certain rarely-executed thread interleavings. Therefore, commonly used debugging methodologies, such as inserting print statements, are no longer sufficient for uncovering concurrency-related bugs. However, many existing bug detection methods, such as dynamic analysis and model checking, have a very high computational cost. In this paper, we introduce a new technique for uncovering concurrency-related bugs from multithreaded Java programs. Our technique uncovers concurrency-related bugs by generating and testing read-write assignment sequences, referred to as value schedules, of a multithreaded Java program. Our value-schedule-based technique distinguishes itself in its ability to avoid exploring superfluous program state space caused by speculative permutation on transitions. Therefore, our technique can achieve a higher degree of POR (Partial Order Reduction) than existing methods. We demonstrate our technique using some programs, with an implementation built using an explicit state model checker called JPF