Improved On-The-Fly Livelock Detection: Combining Partial Order Reduction and Parallelism for DFSFIFO

Until recently, the preferred method of livelock detection was via LTL model checking, which imposes complex constraints on partial order reduction (POR), limiting its performance and parallelization. The introduction of the DFS_FIFO algorithm by Faragó et al. showed that livelocks can theoretically be detected faster, simpler, and with stronger POR. For the first time, we implement DFS_FIFO and compare it to the LTL approach by experiments on four established case studies. They show the improvements over the LTL approach: DFS_FIFO is up to 3.2 times faster, and it makes POR up to 5 times better than with SPIN's NDFS. Additionally, we propose a parallel version of DFS_FIFO, which demonstrates the efficient combination of parallelization and POR. We prove parallel DFS_FIFO correct and show why it provides stronger guarantees on parallel scalability and POR compared to LTL-based methods. Experimentally, we establish almost ideal linear parallel scalability and POR close to the POR for safety checks: easily an order of magnitude better than for LTL.