A Unified Approach for Localizing Non-deadlock Concurrency Bugs

This paper presents UNICORN, a new automated dynamic pattern-detection-based technique that finds and ranks problematic memory access patterns for non-deadlock concurrency bugs. UNICORN monitors pairs of memory accesses, combines the pairs into problematic patterns, and ranks the patterns by their suspiciousness scores. UNICORN detects significant classes of bug types, including order violations and both single-variable and multi-variable atomicity violations, which have been shown to be the most important classes of non-deadlock concurrency bugs. The paper also describes implementations of UNICORN in Java and C++, along with empirical evaluation using these implementations. The evaluation shows that UNICORN can effectively compute and rank the patterns that represent concurrency bugs, and perform computation and ranking with reasonable efficiency.