Processes: Basics, Characteristics, and Applications
A process is a program that is being executed by the CPU. It is the instance of a program that has been loaded into memory and is performing tasks.
Characteristics of Processes:
Process Control Block (PCB): The OS keeps track of each process using a PCB, which stores information such as:
Process ID (PID)
Program counter (indicates the next instruction to be executed)
CPU registers (temporary data storage for the process)
Memory management information (addresses used by the process)
I/O status (the state of any devices used by the process)
States of a Process: A process can be in one of several states during its lifecycle:
New: When the process is created.
Ready: When the process is ready to run but waiting for CPU time.
Running: When the process is currently being executed by the CPU.
Waiting (Blocked): When the process is waiting for an event (like I/O completion).
Terminated: When the process has finished execution.
Process Scheduling: The OS uses scheduling algorithms to determine which process runs next. Common scheduling algorithms include First-Come-First-Serve (FCFS), Round Robin, and Shortest Job First (SJF).
Applications of Processes:
- Multitasking: The OS runs multiple processes at once by quickly switching between them (time-sharing). For example, you can browse the web while listening to music and working on a document, all of which run as separate processes.
- Background Services: Processes can run in the background to handle tasks like updates, network connections, or system monitoring.
