allocator

An allocator is a software component that provides, tracks, and releases resources as needed by a program. In computing, the most common use refers to dynamic memory allocation: requesting blocks of memory from a pool, returning them when they are no longer needed, and keeping information about which blocks are in use.

Memory allocators may operate at different levels and with different strategies. They interface with the program through allocation functions (for example, malloc and free) or language-specific constructs. Allocators balance speed, memory utilization, and safety, and must handle issues such as fragmentation and alignment.

Common allocation techniques include first-fit, best-fit, and next-fit bin-packing; more sophisticated schemes include buddy allocators, slab allocators, and memory arenas. General-purpose allocators aim to be fast and scalable across workloads; specialized allocators optimize for small objects or short-lived data.

In modern systems, operating system kernels implement their own page and slab allocators to manage physical memory, while language runtimes may provide custom allocators for heap management. Allocators are also used in resource management beyond memory, such as CPU time, bandwidth, or I/O quotas, often within scheduling or quality-of-service frameworks.

The allocator model is a common abstraction in programming language design and systems engineering, and many libraries expose configurable allocators to improve performance, memory safety, and determinism.