Jockey

Jockey is an execution record/replay tool for debugging Linux programs. It records invocations of system calls and CPU instructions with timing-dependent effects and later replays them deterministically. It supports process checkpointing to diagnose long-running programs efficiently. Jockey is implemented as a shared-object file that runs as a part of the target process. While this design is the key for achieving Jockey's goal of safety and ease of use, it also poses challenges. This paper discusses some of the practical issues we needed to overcome in such environments, including low-overhead system-call interception, techniques for segregating resource usage between Jockey and the target process, and an interface for fine-grain control of Jockey's behavior.