Where does fork collide?

In an operating system, fork is the system call that creates a new process by duplicating the process that calls it: the running process becomes a parent, and a nearly identical child begins executing from the same point, with its own copy of the parent's memory and its own process identifier. Ritchie and Thompson's 1974 The UNIX time-sharing system described the primitive by which a process splits into two independently executing processes that hold separate memory images but share their open files. The referent is an event inside a computer's kernel, timed in the microseconds a call takes to return, and it is not a split in a codebase, a tactic on a chessboard, or a two-pronged bar of steel.[1]

Unit

A kernel call that duplicates a running process and returns twice

Recovery means

Not applicable

Measured by

Traced by counting the calls and timing their return in the kernel, and by inspecting the parent and child entries in the process table

In open-source software, a fork is a divergent copy of a project's codebase taken up by a separate group who continue to develop it on their own, often after a disagreement over direction, licensing, or governance: the copy shares a common history with the original but is thereafter maintained apart. Robles and González-Barahona's 2012 A comprehensive study of software forks: Dates, reasons and outcomes examined why forks are declared and how rarely they rejoin the parent. The referent is a social and organisational event in a developer community, counted by projects and contributors, and it is not a duplicated process, a chess tactic, or an acoustic resonator.[2]

Unit

A separately maintained copy of a codebase and its community

Recovery means

A fork ends by dying out, by superseding the original, or, more rarely, by merging back into it

Measured by

Studied through repository histories, commit and contributor counts, and the dates and stated reasons a fork was declared

A tuning fork is a two-pronged steel resonator that, when struck, vibrates at a fixed frequency and sounds a nearly pure tone, used as a reference pitch and in hearing tests: the prongs move in opposition while the stem carries the vibration to a surface that radiates the sound. Rossing, Russell, and Brown's 1992 On the acoustics of tuning forks analysed the fork's modes of vibration and its behaviour as a sound source. The referent is a physical object and its resonance, described in hertz, and it is unrelated to a process call, an open-source project, or a chess move.[3]

Unit

A struck two-tine resonator's fixed pitch, in hertz

Recovery means

The tone decays as the vibration damps, and contact through the stem transfers the energy to a soundboard

Measured by

Characterised by its resonant frequency and its rate of decay, using frequency counters, microphones, and modal analysis