Process (computing): Difference between revisions

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[[File:Concepts- Program vs. Process vs. Thread.jpg|thumb|[[Computer program|Program]] vs. Process vs. [[Thread (computing)|Thread]] <br/>[[Scheduling (computing)|Scheduling]], [[Preemption (computing)|Preemption]], [[Context switch|Context Switching]]|400x400px]]

In [[computing]], a '''process''' is the [[Instance (computer science)|instance]] of a [[computer program]] that is being executed by one or many [[thread (computing)|threads]]. There are many different process models, some of which are light weight, but almost all processes (e.g.even entire [[virtual machine]]s) are rooted in an [[operating system]] (OS) process which comprises the program code, assigned system resources, physical and logical access permissions, and data structures to initiate, control and coordinate execution activity. Depending on the OS, a process may be made up of multiple threads of execution that execute instructions [[Concurrency (computer science)|concurrently]].<ref name="OSC Chap4">{{cite book |last1=Silberschatz |first1=Abraham |author-link=Abraham Silberschatz |last2=Cagne |first2=Greg |last3=Galvin |first3=Peter Baer |date=2004 |title=Operating system concepts with Java |edition=Sixth |chapter=Chapter 4. Processes |publisher=[[John Wiley & Sons]] |isbn=0-471-48905-0}}</ref><ref name="Vah96">{{cite book |last=Vahalia |first=Uresh |date=1996 |title=UNIX Internals: The New Frontiers |chapter=Chapter 2. The Process and the Kernel |publisher=Prentice-Hall Inc. |isbn=0-13-101908-2 |url-access=registration |url=https://archive.org/details/unixinternalsnew00vaha }}</ref>

While a computer program is a passive collection of [[Instruction set|instructions]] typically stored in a file on disk, a process is the execution of those instructions after being loaded from the disk into memory. Several processes may be associated with the same program; for example, opening up several instances of the same program often results in more than one process being executed.