In computing, a process is an instance of a program in execution. It is a dynamic entity that represents the execution of a set of instructions within the computer's memory. A process has its own memory space, system resources, and state, and it operates independently of other processes. Multiple processes can run concurrently in a computer system.
Key characteristics of a process include:
Program Code: A process is associated with a specific program or application code that it executes. The program code is loaded into the process's memory space.
Memory Space: Each process has its own address space, which includes the code, data, and stack segments. The memory space is isolated from the memory spaces of other processes to prevent interference.
System Resources: A process can use various system resources, such as CPU time, files, network sockets, and input/output devices. These resources are allocated to the process by the operating system.
Execution State: A process has an execution state that reflects its progress. It can be in states like running, ready, or blocked, depending on whether it is actively executing instructions, waiting for input/output, or ready to execute.
Identifier: Each process is assigned a unique identifier, often called a Process ID (PID). This identifier distinguishes one process from another.
Environment: Processes can have their own environment, including variables, file descriptors, and other settings that affect their behavior.
Independence: Processes operate independently of each other. They do not share their memory space directly but may communicate through inter-process communication mechanisms provided by the operating system.
Processes are fundamental to the multitasking capabilities of modern operating systems. By allowing multiple processes to run concurrently, an operating system can give the illusion that several programs are running simultaneously, even on a single processor system. The operating system's scheduler manages the execution of processes, determining which process gets CPU time and in what order.
In contrast to processes, threads are lighter-weight entities that exist within a process and share the same memory space. Threads can be thought of as the smallest units of execution within a process.
