Process Hierarchy in Operating System

In an operating system, the process hierarchy refers to the organization and structure of processes within a system. It establishes the relationship between parent and child processes, creating a hierarchical structure.

Here’s a detailed explanation of process hierarchy in an operating system:

1. Parent-Child Relationship: In a process hierarchy, each process except for the root process has a parent process from which it is created. The parent process is responsible for creating, managing, and controlling its child processes. This creates a hierarchical relationship where processes form a tree-like structure.
2. Root Process: The root process is the top-level process in the hierarchy and has no parent process. It is usually the first process that is created when the operating system starts. All other processes are descendants of the root process.
3. Child Processes: Each process, except for the root process, can create one or more child processes. When a process creates a child process, the child process inherits certain attributes and resources from its parent, such as the memory space, file descriptors, and environment variables.
4. Process Group: Processes within the same process hierarchy can be organized into process groups. A process group is a collection of related processes that can be managed and controlled collectively. Process groups enable operations such as signaling and process control across multiple processes.
5. Process Tree: The process hierarchy forms a tree-like structure, often referred to as the process tree. The root process is at the top of the tree, and child processes branch out from their parent processes. The process tree represents the relationships and dependencies between processes within the system.
6. Process ID (PID): Each process in the system is assigned a unique process identifier (PID) that distinguishes it from other processes. PIDs are used for process management and identification purposes, allowing the operating system to track and manipulate processes.
7. Process Termination: When a process terminates, either voluntarily or due to an error or completion, its resources are released, and it is removed from the process hierarchy. If a parent process terminates before its child processes, the orphaned child processes may be adopted by a system-defined parent process called the “init” process.

The process hierarchy in an operating system facilitates process management, resource allocation, and control. It allows for the organization and coordination of processes, enabling the execution of complex applications and multitasking. The hierarchical structure helps establish relationships and dependencies between processes, ensuring orderly execution and efficient resource utilization.