Pipeline (Unix) - Implementation

Implementation

In most Unix-like systems, all processes of a pipeline are started at the same time, with their streams appropriately connected, and managed by the scheduler together with all other processes running on the machine. An important aspect of this, setting Unix pipes apart from other pipe implementations, is the concept of buffering: for example a sending program may produce 5000 bytes per second, and a receiving program may only be able to accept 100 bytes per second, but no data is lost. Instead, the output of the sending program is held in a queue. When the receiving program is ready to read data, the operating system sends its data from the queue, then removes that data from the queue. If the queue buffer fills up, the sending program is suspended (blocked) until the receiving program has had a chance to read some data and make room in the buffer. In Linux, the size of the buffer is 65536 bytes.