Essay --

Process: A computer Process means a program which is being executed. some are administrative, providing ancillary services for the remainder of the system and some are application processes. Each process has its own address space, or memory allocated to it A program may contain more than one process. E.g. we open MSWORD & then we may work with copy, paste, cut etc commands which are its sub processes or child processes. Some times a process is also called a task . A thread is a light process of executes during program execution through a program. E.g. Error messages, Alerts etc , which may appear during program execution. Multiple threads can exist within a process, but they all share a common address space. A process can be in one of three states: Running Blocked Ready (or Queued) There are five different states of a process New - The process is being created. Running - Instructions are being executed. Waiting - Waiting for some event to occur. Ready - Waiting to be assigned to a processor. Terminated - Process has finished execution. Processes must communicate with one another in computer environment e.g. we may open a MSWord & MS-Excel we perform a copy operation in MSWord & then use Paste Special function in MS-Excel , here inter process communication is being performed. That is why it is very necessary for a processes that must coordinate activities to achieve a common objective. we can also define Inter Process Communication as a set of techniques for the exchange of data among two or more threads in one or more processes. Processes may be running on one or more computers connected by a network. IPC techniques are divided into methods for message passing, synchronization, shared memory, and r... ...he scheduler,& Algorithm it uses is called the scheduling algorithm. The following are the main objectives of Scheduling: Make best use of available system resources, Give preference to those processes which are holding the key resources. Give preference to processes which are having good behavior. CPU Scheduler basically selects the process from the different processes which are residing in the memory and are ready to execute, & then allocates the CPU to one of them. The Scheduling may be Preemptive or Non-Preemptive: Non-preemptive Scheduling Once CPU has been allocated to a process, the process keeps the CPU until Process exits OR Process switches to waiting state Preemptive Scheduling Process can be interrupted and must release the CPU. Need to coordinate access to shared data E.g. when we use â€Å"Ctrl + Alt + Delete† to terminate the process forcefully.