Process Management

Process Management

A process is defined as the event of the running programs. Everything running on the computer including services and applications are all a process. Process management can be described as how the operating system manages the multiple processes running. Multiprocessing operating systems such as Mac, Windows, and UNIX/Linux must manage and control many processes simultaneously. Every process contains one or more threads, and the Windows thread is the basic executable unit. Threads are scheduled on the basis of these factors: availability of resources such as CPUs and physical memory, priority, fairness, etc. Windows has long supported multiprocessor systems, so threads can be allocated to separate processors within a computer.

Each thread in a process shares code, global variables, environment strings, and resources. Each thread is independently scheduled, and a thread has the following elements:

* A stack for procedure calls, interrupts, exception handlers, and automatic storage.

* Thread Local Storage (TLS) - An array like collection of pointers giving each thread the ability to allocate storage to create its own unique data environment.

* An argument on the stack, from the creating thread, which is usually unique for each thread.

* A context structure, maintained by the kernel, with machine register values.

A UNIX process is comparable to a Windows process. Threads, in the form of POSIX P threads, are now almost universally available and used in UNIX and Linux. P threads provides features similar to Windows threads, although Windows provides a wider collection of functions.

Vendors and others have provided various thread implementations for many years; they are not a new concept. P threads is, however, the most widely used standard, and proprietary implementations are long obsolete. There is an open source P threads library for Windows.

UNIX®/Linux®

The UNIX operating system provides an introduction to process control,...