Hotstart

Hotstart, often written hot start, is a term used across several technical domains to denote starting a process from an existing, partially prepared state rather than from a fully fresh condition. The core idea is to leverage prior activity or heat, data, or state to reduce startup time or to improve performance. The phrase is related to, but distinct from, cold start (starting from zero state) and warm start (partial preparation).

In computing and numerical computation, hot start refers to initializing a procedure with a solution or state obtained from a previous run. This is common in iterative solvers, optimization, simulation, and machine learning workflows. Using a hot start can dramatically accelerate convergence when problem parameters have not changed much, but it can also lead to poor results if the previous state is not representative.

In software and systems engineering, hot-start techniques include preloading data into caches, keeping services warm, or reusing configuration and session state after a restart. Such approaches reduce startup latency and improve responsiveness, particularly for long-running services or data-intensive tasks.

In aviation and propulsion, hot start is a specific start condition where the engine remains hot and fuel flow or timing is not promptly adjusted, leading to high combustion temperatures. It is considered abnormal and potentially damaging, requiring prescribed shutdown or corrective actions and adherence to engine manufacturer procedures.

Related terms include warm start and cold start, which describe progressively less prior state being used. In planning and control, hot-start strategies are weighed against safety, reliability, and the risk of stale or biased initial states.