Extending the Legio Resilience Framework to Handle Critical Process Failures in MPI

The presence of faults in distributed executions can compromise the production of results without proper fault management techniques. The current de-facto standard for inter-process communication, MPI, lacks these features, precluding its effectiveness at a massive scale. Previous efforts produced all-in-one frameworks for fault management, but most of these works leverage checkpoint and restart functionalities, impacting the performance and scalability of the executions. Unlike those, the Legio framework adopts a graceful degradation solution, sac-rificing result accuracy for faster recovery and lower overhead. Still, it cannot handle all the faults: there may be some critical processes whose failure irremediably compromises the result of the computation. With this work, we extend the Legio framework to support critical process faults, combining the benefits of checkpoint and restart solutions with a graceful degradation approach. The experimental campaign shows that our extension does not introduce significant overheads in the executions while correctly managing the failure of critical processes.