OutBuffer

An out buffer, or output buffer, is a memory region used to store data that is destined for an output sink such as a file, network socket, device, or display. It serves as a staging area between data producers and the slower or irregular consumer, enabling smoother data flow and reducing the number of I/O operations.

Typically an out buffer maintains capacity, current size, and a pointer to the data; it may be implemented as a contiguous block, a ring (circular) buffer, or a linked list of blocks. It can be owned by a producer, a consumer, or a dedicated I/O layer. Operations include writing data into the buffer, checking for space, and flushing the buffered content to the sink. Some designs support zero-copy semantics by allowing the sink to take ownership of a buffer chunk.

In asynchronous or event-driven systems, the out buffer decouples producer speed from sink speed; when full, producers may be asked to slow down or backpressure is applied. Flushing may occur when the buffer reaches a threshold or when an explicit flush is requested; partial writes are common and must be handled to ensure data integrity and progress.

Common use cases include network send buffers, file write buffering, and multimedia streaming pipelines, where accumulated output can be transmitted in larger blocks for efficiency. Out buffers are often paired with an input buffer (InBuffer) to form a buffering subsystem. They are also a key consideration in performance-sensitive code, where choices around memory allocation, alignment, and synchronization influence latency and throughput.

While not a universal standard, the term out buffer appears in documentation and source code across programming languages and platforms, used to describe the component that aggregates data for output. See also InBuffer, circular buffer, and buffering.