coreonce

Coreonce is a term used in software engineering to describe a mechanism that ensures a particular computation or initialization is performed exactly once, across threads or cores, during a program’s execution. The concept is commonly employed to implement lazy initialization, singleton patterns, and one-time setup tasks that must be thread-safe.

At its core, coreonce relies on a primitive that coordinates multiple execution contexts so that only the first invocation executes the target code, while all other invocations observe the completed state and skip or immediately return the result. Implementations typically use atomic operations, memory barriers, or mutexes to guarantee single execution and to publish the initialized state to other threads.

In practice, many programming languages provide a similar primitive under different names, such as Go’s sync.Once, Rust’s Once and OnceCell, or C++’s std::call_once. While some libraries or projects brand their own one-time initialization facilities as coreonce, there is no single universal standard for the term. Common use cases include initialization of global resources, loading configuration, and performing expensive computations that should not be repeated.

Limitations and caveats include the potential for deadlocks or race conditions if the initialization code panics or throws, or if memory visibility is not properly managed. There is also an inherent synchronization overhead, though efficient implementations minimize impact through lock-free designs or fine-grained synchronization where supported.

Historically, coreonce as a concept arises from broader discussions of concurrency primitives and design patterns rather than from a formal specification. See also: singleton, lazy initialization, call_once, concurrency control.