resumability

Resumability is the property of a system, task, or computation that allows pausing execution and later continuing from a saved intermediate state. It aims to avoid restarting from the beginning after an interruption. Achieving resumability typically requires a persistent representation of progress, a stable way to apply saved state, and a failure model that supports recovery.

Techniques used to enable resumability include checkpointing, where full or incremental state is captured at intervals; serialization of program state for later restoration; and event sourcing, which records changes as a sequence of immutable events. In software design, resumable constructs such as generators, coroutines, and asynchronous workflows provide explicit points where execution can be paused and resumed.

Resumable behavior is relevant in several contexts. Long-running simulations and data analyses benefit from checkpoints that permit pause-and-resume across sessions. Distributed and cloud environments rely on durable state and idempotent restarts to recover from failures. Network transfers and downloads may use partial data and byte-range requests to resume after interruptions.

Advantages include fault tolerance, reduced wasted work, and greater control over long processes. Trade-offs involve additional storage and processing overhead, complexity in maintaining consistent state, and the need for careful design to ensure idempotence and determinism during restarts.

Resumability is a broad concept in computing and is closely related to persistence, checkpointing, and fault-tolerant systems.