faulthandling

Faulthandling, also referred to as fault handling, is the set of techniques and mechanisms used to detect, report, isolate, and recover from faults in a system. The goal is to maintain operation or provide safe degradation in the presence of errors or failures.

In software engineering, fault handling includes exception handling, error codes, input validation, and structured logging. It encompasses strategies such as fail-fast versus fail-safe design, defensive programming, and robust API design. Typical techniques include retries with backoff, timeouts, circuit breakers, idempotent operations, and graceful degradation. Observability through monitoring and tracing is integral to identifying faults and preventing cascading failures.

In hardware and distributed systems, fault handling relies on redundancy and recovery mechanisms such as replication, failover, checkpointing, and hot spares. Error-detecting and correcting codes (ECC), watchdog timers, health checks, and fault isolation help contain faults and limit their impact on service continuity.

Designing fault handling involves trade-offs among performance, complexity, and consistency. Some systems aim for fault tolerance, continuing operation despite faults, while others prioritize safe failure modes or quick recovery. Safety-critical contexts may require formal methods, redundancy, and rigorous testing.

As a concrete tool example, Python provides a faulthandler module that can dump Python stack traces in the event of crashes or fatal signals to aid debugging. Similar facilities exist in other languages and platforms to aid diagnosis and recovery.