Process (data-processing)

See also: Process

A process (in English, process ), in Data-processing, is defined by:

  • a whole of instructions to be carried out (a program);
  • a memory capacity for the data of work;
  • possibly, other resources, like descriptors of files, ports network, etc

A computer equipped with a Operating system at time-sharing is able to carry out several processes in a “nearly simultaneous” way. If there are several processors, the execution of the processes is distributed in an equitable way on these processors.

The direction of process must be taken as something which takes time, therefore which has a beginning and (sometimes) an end. A process perhaps started by a user via a peripheral or by another process: the applications of the users are (whole of) processes.

The operating system is charged to allocate the resources (memories, time processor, inputs/outputs) necessary to the processes and to ensure that the operation of a process does not interfere with that of the others (insulation). It can also provide a API to allow the Communication inter-process (IPC).

In addition to the multiplexing of the material resources, the system can control the access of the processes to the resources according to a matrix of rights (permissions of access) and also associate the processes to the users, who are the récipendiaires of a whole of rights of access: a process has the rights of the user who started it.

A process can stop several manners:

  1. normal Stop (voluntary).

  2. Stop for error (voluntary).
  3. Stop for fatal error (involuntary).
  4. the process is stopped by another process (involuntary).

The majority of the systems offer the distinction between heavy process (such as we described them), which a priori are completely isolated from/to each other, and light Processus S ( Threads in English), which in common has a memory capacity (and other resources).

In the case of process comprising several light Processus S (or following the expression often used multi-thread) there exists a state of the processor (a context of execution) distinct for each light process.

Internal bonds

  • Multi-task
  • light Process
  • Zombie

External bond

  • Tutorial on the operation of the processes under GNU/Linux

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