Input/output completion port

IOCP stands for Input Ouput Completion Port. It is a technique for performing multiple simultaneous asynchronous input/output operations in a computer operating system. An input/output completion port object is created and associated with a file descriptor. When I/O services are requested on the file descriptor, completion is indicated by a message queued to the I/O completion port. A process requesting I/O services is not notified of completion of the I/O services, but instead checks the I/O completion port's queue to determine the status of its I/O requests. The I/O completion port manages multiple threads and their concurrency.