Characterizing Non-deadlock Concurrency Bug Fixes in Open-source Java Programs

Fixing a non-deadlock concurrency bug is a difficult job that sometimes introduces additional bugs and requires a long time. To overcome this difficulty and efficiently perform fixing jobs, engineers should have broad knowledge of various fix patterns, and the ability to select the most proper one among those patterns based on quantitative data gathered from real-world bug databases. In this paper, we provide a real-world characteristic study on the fixes of non-deadlock concurrency bugs to help engineers responsible for program maintenance. In particular, we examine various fix patterns and the factors that influence the selection of those patterns with respect to the preexistence of locks and failure types. Our results will provide useful information for engineers who write bug patches, and researchers who study efficient testing and fixing techniques.