InterProcess

Interprocess communication (IPC) refers to a set of mechanisms that allow independent processes to exchange data and coordinate actions. IPC enables information sharing, synchronization, and cooperation between processes that run concurrently and may have separate address spaces. It is a core aspect of operating systems and multi-process software.

Common IPC mechanisms include pipes (anonymous and named/FIFO), message queues, shared memory, semaphores and other synchronization primitives, memory-mapped files, and inter-process signaling. Sockets provide cross-machine IPC, enabling communication between processes on different hosts. High-level abstractions include remote procedure calls and data streams.

IPC can be synchronous or asynchronous, blocking or non-blocking, and supports one-to-one, one-to-many, or many-to-many communication patterns. Shared memory is fast but requires explicit synchronization; pipes and message queues impose ordering but may incur copying overhead. Sockets and RPCs support network transparency, allowing communication across machine boundaries.

Platform variations exist in IPC implementations. POSIX-compliant systems offer pipes, FIFOs, POSIX message queues, named semaphores, and POSIX shared memory. Windows provides named pipes, mailslots, shared memory via file mappings, and various synchronization primitives. Security concerns include access permissions, data serialization (marshalling), and potential deadlocks or data races, which must be managed through careful design and resource lifetime handling.

Applications of IPC include operating system process coordination, server architectures, multimedia pipelines, and microservice communication. When designing IPC schemes, developers consider data size, latency requirements, synchronization needs, resource lifetimes, and potential contention to ensure correctness and performance.