memorymanagement

Memory management is a set of techniques for allocating, tracking, and reclaiming primary memory for programs. It spans the operating system’s handling of physical memory and, in managed languages, the runtime’s allocator. Its goals are isolation between processes, efficient use of memory, and fast access to data.

Common approaches include contiguous allocation, paging, and segmentation. Contiguous allocation gives each process a single block, but can cause external fragmentation. Paging divides memory into fixed-size units, enabling noncontiguous placement, while segmentation groups memory by logical units. Virtual memory combines paging with page tables to map addresses and often relies on a translation lookaside buffer for speed.

Fragmentation is addressed by techniques such as compaction and the buddy system. Garbage collection in managed runtimes reclaims unused objects automatically, using algorithms like mark-and-sweep, stop-and-copy, or generational collectors. Reference counting provides another approach, though it struggles with cycles in some scenarios.

Hardware support comes from the memory management unit, which enforces protection and translates addresses. The operating system maintains page tables, frame lists, and allocation data structures, and may swap pages to disk. Modern systems optimize for locality, security, and multi-core or virtualized environments.

Trends include demand paging, memory compression, and non-uniform memory access awareness. In cloud and container environments, memory quotas and overcommitment influence design and tuning. Effective memory management balances latency, throughput, and isolation while adapting to diverse workloads.