Process management (computing): Difference between revisions

Revision as of 02:05, 15 October 2024

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{{OS}}

A process is a program in execution, and an integral part of any modern-day [[operating system]] (OS). The OS must allocate resources to [[process (computing)|processes]], enable processes to share and exchange information, protect the resources of each process from other processes and enable synchronization among processes. To meet these requirements, theThe OS must maintain a [[data structure]] for each process, which describes the state and resource ownership of that process, and which enables the OSoperating system to exert control over each process.

== Multiprogramming ==

In any modern operating system, there can be more than one instance of a [[computer program|program]] loaded in memory at the same time. For example, moreMore than one user can be executing the same program, with each user having separate copies of the program loaded into memory. With some programs, itIt is possible to have one copy loaded into memory, while several users have shared access to it so that they can each execute the same program-code. Such a program is called [[Reentrant (subroutine)|re-entrant]].{{Relevance inline|date=November 2023}} At a given instant, the [[central processing unit|processor]] at any instant can only be executing one instruction from one program, but several processes can be sustained over a period of time by assigning each process to the processor at intervals while the remainder become temporarily inactive. The execution of multiple processes over a period of time, rather than simultaneously, is known as concurrent execution.

A [[multiprogramming]] or [[Computer multitasking|multitasking]] OS is a system that can execute many processes concurrently. Multiprogramming requires that the processor be allocated to each process for a period of time and de-allocated or issued at an appropriate moment. If the processor is de-allocated during the execution of a process, it must be done in such a way that it can be restarted later as easily as possible.