bufSize

Bufsize, short for buffer size, is the size in bytes of a temporary storage area used to hold data during input or output operations. Buffers are employed to decouple speeds between producers and consumers, to absorb bursts, and to reduce the number of system calls or kernel I/O operations.

In programming languages and libraries, the buffer is allocated and filled by the I/O API. The parameter controlling the size is often named bufsize, buffer_size, or buffering. The default size varies by language and implementation; for example, C standard I/O uses a default buffer size defined by BUFSIZ; many higher-level languages allow configuring the size when opening a stream or performing a read/write.

Choosing bufsize involves trade-offs: small buffers minimize memory usage and latency but increase overhead and CPU time; large buffers can improve sequential throughput by reducing system call overhead but consume more memory and may increase end-to-end latency for small reads.

In network I/O, buffers are associated with sockets; larger send/receive buffers can improve throughput on high-bandwidth links but may add delay and jitter if the application is latency-sensitive.

Tips: start with a few kilobytes to a few hundred kilobytes; adjust based on measurements; ensure that the buffer aligns with underlying storage or network characteristics; avoid excessively large buffers that waste memory.

The term bufsize is also a common variable name in code that handles streaming or file transfer.