Verifying Exception-Handling Code in Concurrent Libraries

Concurrency errors due to poorly handled exceptions are common. Developers often make mistakes in writing proper code logic to relinquish the resources in the exception-handlers and cleanup blocks such as finally in Java. Our observations suggest that these mistakes often go unnoticed because the exception-handling code is generally not tested in the development phase. These errors materialize when the exception handlers execute within the production environment. Therefore, verifying multi-threaded programs augmented with their exception handlers is necessary to guarantee their correctness. This paper proposes a dynamic technique to verify exception-handling code in concurrent libraries. The technique detects the presence of deadlocks originating from exception-handling code. We also present a prototype called Lumina,that implements our technique to demonstrate that it can detect the deadlocks effectively, unlike the state-of-the-art dynamic verifier JavaPathfinder (JPF).