Detection of Java Basic Thread Misuses Based on Static Event Analysis

The fundamental asynchronous thread (java.lang.Thread) in Java can be easily misused, due to the lack of deep understanding for garbage collection and thread interruption mechanism. For example, a careless implementation of asynchronous thread may cause no response to the interrupt mechanism in time, resulting in unexpected thread-related behaviors, especially resource leak/waste. Currently, few works aim at these misuses and related works adopt either the dynamic approach which lacks effective inputs or the static path-sensitive approach with high time consumption due to the path explosion, causing false negatives. We have found that the behavior of threads and the interaction between threads and its referencing objects can be abstracted. In this paper, we propose an event analysis approach to detect the defects in Java programs and Android apps, which focuses on the existence or the order of the events to reduce the false negatives. We extract the misuse-related events, containing the thread events and the destroy events of the object referenced by the thread. Then we analyze the events with loop identification, happens-before relationship construction and alias determination. Finally, we implement an automatic tool named Leopard and evaluate it on real world Java programs and Android apps. Experiments show that it is efficient when comparing with the existing approach (misuse: 723 vs 47, time: 60s vs 30min), which also outperforms the existing work in precision. The manual check indicates that Leopard is more efficient and effective than existing work. Besides, 66 issues reported by us have been confirmed and 21 of them have been fixed by developers.