Operating systems (OS) play a crucial role in managing and coordinating various aspects of computer systems. One of the fundamental responsibilities of an operating system is process management, which involves creating, scheduling, and controlling processes.
Process in Operating System
A process can be thought as a program in execution, but a program by itself is not a process. Process is nothing but a set of instruction to be executed. Multiple instances of a single process can be running at any given time and also a process may create sub-processes with time. Processes may need certain resources like, CPU time, memory, files and access to other devices.
Process is a set of instruction; it can be considered that a batch job is a process. CPU execute instructions in a process in a sequential manner, one instruction after another until the process is complete.
A process is more than the program code. It includes the current activity which is the value of the program counter, and the contents of the processor’s registers, a process stack containing temporary data and a data section containing global variables.
Process management operations
- Creation and Deletion of Processes
- Suspension and Resumption of Processes
- Process Synchronization
- Process Communication
- Deadlock Handling
1. Creation and Deletion of Processes
Operating systems are responsible for creating and deleting processes. A process is essentially a program in execution, encompassing a set of instructions. The OS initiates the creation of new processes when requested by users or as a result of system activities. Similarly, processes that have completed their execution or are no longer needed are terminated and deleted by the operating system.
2. Suspension and Resumption of Processes
In addition to creation and deletion, operating systems handle the suspension and resumption of processes. When a process is waiting for certain events, such as input/output activities or external signals, the operating system can suspend its execution and allocate system resources to other processes. Once the awaited events occur, the suspended process can be resumed and continue its execution.
3. Process Synchronization
Process synchronization refers to the coordination of activities among concurrent processes to ensure data consistency and prevent conflicts. Operating systems provide mechanisms, such as locks, semaphores, and monitors, to facilitate synchronization. These mechanisms allow processes to coordinate their access to shared resources and avoid scenarios like race conditions or data corruption.
4. Process Communication
Inter-process communication (IPC) is a crucial aspect of process management. Operating systems provide various communication mechanisms, such as pipes, shared memory, message queues, and sockets, to facilitate data exchange and collaboration between processes. IPC enables processes to interact, share information, and synchronize their activities.
5. Deadlock Handling
A deadlock occurs when two or more processes are unable to proceed because each is waiting for a resource held by another process. Operating systems employ strategies to detect and resolve deadlocks, such as resource allocation algorithms, deadlock prevention techniques, and deadlock detection and recovery mechanisms. These measures ensure that processes can continue their execution and avoid system-wide halts.
Processes can exist in several states during their lifecycle. The typical process states include:
- New: In the “New” state, a process is being created. The operating system initializes the necessary data structures and allocates resources to the process. This includes assigning a unique process identifier (PID) and setting up the initial environment for the process.
- Running: When a process is in the “Running” state, it means that the instructions within the process are actively being executed by the CPU. The operating system allocates the CPU time to the process, allowing it to progress through its instructions.
- Waiting: In the “Waiting” state, a process is temporarily halted and waiting for a particular event or resource. This event could be user input, completion of an I/O operation, or a signal from another process. While waiting, the process releases the CPU and may be placed in a suspended or blocked state until the event it is waiting for occurs.
- Ready: The “Ready” state indicates that a process is prepared for execution and is waiting to be assigned to a CPU. When multiple processes are in the ready state, the operating system’s scheduling algorithm determines which process will be allocated CPU time next. Processes in the ready state are stored in a ready queue and compete for CPU resources.
- Terminated: When a process completes its execution, it enters the “Terminated” state. At this point, the operating system performs necessary cleanup tasks, releases allocated resources, and deallocates the process’s data structures. The process may also communicate its termination status to the parent process or the operating system itself.
It’s important to note that process states can be dynamic, and a process may transition between different states based on external events or internal actions. For example, a running process may be interrupted by a higher-priority process, causing it to move to the waiting or ready state.
Process state transitions are managed by the operating system’s process scheduler, which determines the order and timing of process execution based on various scheduling algorithms. Efficient process management ensures optimal resource utilization and system responsiveness.
Process management is a vital aspect of operating systems, enabling the creation, scheduling, and coordination of processes. Operating systems handle various operations related to process management, including process creation and deletion, suspension and resumption, synchronization, communication, and deadlock handling. Understanding the different states, a process can go through provides valuable insights into the inner workings of an operating system, helping us appreciate its role in efficient and reliable computing.