Lecture Operating Systems - Chapter 3: Processes

Modern computing relies heavily on efficient resource management. Understanding how operating systems manage concurrent execution is fundamental, and the concept of a "process" is central to this. This chapter delves into the core principles of process management, covering their definition, lifecycle, scheduling mechanisms, and inter-process communication techniques. It aims to equip readers with a foundational understanding necessary for developing robust and efficient software within an operating system environment. The discussion will range from basic process concepts to advanced topics like client-server communication.

Students and professionals in computer science, software engineering, and anyone interested in the foundational aspects of operating systems and system programming.

This chapter provides a comprehensive exploration of processes within the context of operating system concepts. It begins by defining a process as a program in execution, detailing its multi-part structure including the text, data, heap, and stack sections, and distinguishing it from a passive program. The document then outlines the various process states—New, Running, Waiting, Ready, and Terminated—and illustrates their transitions through a state diagram, highlighting the dynamic nature of process execution. A significant portion is dedicated to the Process Control Block (PCB), explaining its role as a repository for essential process information such as the process state, program counter, and CPU registers, which is crucial for the operating system's management. The introduction of threads expands on the idea of multiple execution paths within a single process. The chapter further explores process scheduling, describing how the process scheduler manages scheduling queues (ready and wait queues) to maximize CPU utilization. It meticulously explains the context switch mechanism, where the CPU saves the state of one process and loads another, emphasizing that this is an overhead, and how hardware support can optimize it. Finally, the discussion covers operations on processes, including process creation and process termination. It elaborates on how parent processes create child processes, the concept of a Process Identifier (PID), and different resource sharing models between parent and child processes. The chapter also touches upon execution options (concurrent or sequential) and address space considerations during process creation. The underlying mechanisms for inter-process communication (IPC), including shared-memory systems and message-passing systems, are introduced, along with examples like client-server communication using sockets and remote procedure calls, providing a holistic view of process management in modern operating systems like Linux.