Fork (operating System) - Forking in Other Operating Systems

Forking in Other Operating Systems

The fork mechanism (1969) in Unix and Linux maintains implicit assumptions on the underlying hardware: linear memory and a paging mechanism that enable an efficient, memory copy operation of a contiguous address range. In the original design of the VMS (now OpenVMS) operating system (1977), a copy operation with subsequent mutation of the content of a few specific addresses for the new process as in forking was considered risky. Errors in the current process state may be copied to a child process. Here, the metaphor of process spawning is used: each component of the memory layout of the new process is newly constructed from scratch. From a software-engineering viewpoint this latter approach would be considered more clean and safe, but the fork mechanism is still predominant due to its efficiency. The spawn metaphor was later adopted in Microsoft operating systems (1993).