What Is an Arena Allocator?

An arena allocator, also called a region or bump allocator, allocates by advancing a pointer through a reserved block, which makes each allocation nearly free. Individual objects are not freed one by one; instead the whole arena is discarded or reset at once. This fits work with a clear shared lifetime, such as handling a single request.

Why it matters

Bulk-freeing an entire arena is far cheaper than tracking and releasing many objects, and it eliminates a class of leaks. The constraint is that everything in the arena shares one lifetime, so it suits phase-based work.

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