Memorysharing

Memorysharing refers to techniques that allow multiple processes, and in some cases multiple machines, to access a common region of memory in order to exchange data efficiently. On a single system, memorysharing enables inter-process communication by reducing data copies and avoiding intermediary buffers. When extended across machines, it supports distributed memory sharing, often via hardware features or software abstractions that present shared memory across networked nodes.

On local systems, common mechanisms include POSIX shared memory (shm_open, mmap with MAP_SHARED) and System V shared memory (shmget, shmat), as well as memory-mapped files that back a shared region. Anonymous memory mappings with MAP_SHARED allow several processes to view the same physical pages. Synchronization primitives such as semaphores, mutexes, futexes, or memory barriers are typically required to coordinate access and ensure data consistency across readers and writers.

Distributed or networked memorysharing aims to extend shared memory concepts beyond a single host. Approaches include distributed shared memory (DSM) systems, remote direct memory access (RDMA) over high-speed networks, and other cache-coherence or memory-virtualization techniques. These methods seek to provide a coherent shared memory view across processes on different machines, often with explicit or implicit coherence protocols and latency considerations.

Benefits of memorysharing include reduced data copying, lower latency, and higher throughput for certain workloads such as databases, real-time media processing, and high-performance computing. Challenges involve synchronization complexity, memory consistency, security and access control, fragmentation, and portability across operating systems and hardware.