recvcount

recvcount is a term used in programming to denote the number of data units actually received by a receive operation. It is not a fixed function or API name, but a commonly used variable or value in examples, libraries, and documentation to express how much data has been read from a source. The concept applies across I/O, networking, and inter-process communication, where a caller may request a certain amount of data but receive less due to timing, buffering, or protocol constraints.

In network sockets, receive operations typically return the number of bytes successfully read from a connection. When coding with functions like recv (or read on some systems), a variable named recvcount is often used to store this return value. A positive recvcount indicates the amount of data actually received, 0 signals that the peer has performed an orderly shutdown, and -1 indicates an error. Partial reads are common, so robust code loops to obtain the desired amount of data or handles the shorter read appropriately.

In the Message Passing Interface (MPI), the meaning of recvcount appears in explanations about MPI_Recv. The call specifies a maximum count of elements to receive, but the actual number of elements received is obtained from the status object after completion, typically via MPI_Get_count. In this context, the retrieved value is sometimes referred to as the recvcount, and it can be smaller than the initial request if data is less than requested or when using derived datatypes.

Common considerations include handling partial reads, checking for errors, and ensuring buffers are sized appropriately for the possible recvcount. See also: recv, read, MPI_Get_count, status.