N Process Solution using Semaphore

Duration: 8 min

This video lesson is available to enrolled students.

Return to /learn/MPPSC-ASSISTANT-PROFESSOR-COMPUTER-SCIENCE-PAPER-2/operating-system/process-synchronization/semaphores-ordering/asset-n-process-solution-using-semaphore after enrolling

Inside: a video lesson and guided study material.

Module outline

  1. About Course: About the Course
  2. Paper 1 | General Studies: State Wise GK
  3. Paper 1 | Information and Communication Technology: Role of Internet and Web Services, Security in Mobile and Wireless Computing
  4. Paper 1 | Current Affairs: GK- Current Affairs
  5. Paper 2 | Discrete Mathematical Structure: Digital Systems & Boolean Basics, Logic Gates & Hardware, Boolean Expression, Boolean Minimization, Set Theory, Relations, Functions, Graph Theory, Group Theory, Propositional and Predicate Logic, Probability
  6. Paper 2 | Digital Computer Organization And Architecture: Number System, Number Representation, Sequential Circuits, Combinational Circuit, Basics of COA, Floating Point Rep, Cache Memory Organization, Input Output Organisation, Pipelining, Instr Formats & Modes, Register Transfer and Microoperations, Control Unit Design, Programming the Basic Computer
  7. Paper 2 | C Programming: C Fundamentals, Control Flow, Functions, Arrays & Pointers, Storage Classes, Structures & Enums, DMA, Macros, Scoping & File Handling
  8. Paper 2 | Programming Languages & Object-Oriented Programming Concepts: Java, OOPS with C++, Java Fundamentals, Array, String, IO & References
  9. Paper 2 | Python: Introduction to Python, Tokens, Variables, Data Types, I/O, Operators & Expressions, Control Flow & Looping, Collections & Strings, Functions & Modules, File Handling & Data Analysis
  10. Paper 2 | Data Structure And Algorithms: Introduction to DS, Array, Stack, Queue, Linked List, Tree, Graphs, Hashing, Algorithm Analysis, Time Complexity Analysis, Sorting Algorithms, Greedy Algorithms, Minimum Spanning Trees, Advanced Algorithms
  11. Paper 2 | Operating System: Introduction to OS, Process Management, CPU Scheduling, Process Synchronization, Deadlock, Threads & Process Creation, Memory Management, Virtual Memory, Disc Scheduling, File Management, Unix OS
  12. Paper 2 | Theory Of Computation: Introduction to TOC, Deterministic FA (DFA), Non-Deterministic FA, Regular Expressions, Grammar, Regular Language Properties, Moore & Mealy Machines, Pushdown Automata & CFG, Turing Machines, Complexity Theory
  13. Paper 2 | Compiler Design: Intro to Compilers, Lexical Analysis, Grammar & CFG, Syntax Analysis: Top-Down, Syntax Analysis: Bottom-Up, Semantic Analysis & SDT, Intermediate Code Gen, Code Optimization, Run Time Environment
  14. Paper 2 | Database Management System: Basics of DBMS, ER Diagram, Relational Model & Functional Dependencies, Keys & Integrity Constraints, Normalization (1NF - BCNF), Decomposition Properties & 4NF, Relational Algebra, SQL, Transaction Management, Concurrency Control, Database Recovery, Database Security & Authorization, Enhanced Data Models
  15. Paper 2 | Computer Network And Information Security: Introduction to CN, Data Communication, Application Layer, Hardware basics, Cyber Threats and Malware Attacks, Network Security, DLL: Access Control, DLL: Flow Control, DLL: Error Control, DLL: Framing, Data Link Layer - Ethernet, Net Layer: IPv4 & Proto, Net Layer: IP Addressing, Net Layer:Routing Protocol, Transport Layer Services, TL: Congestion & UDP
  16. Paper 2 | Software Engineering: Fundamentals of Software Engineering, Software Requirements and Quality Assurance, Software Design, Estimation and Metrics, Software Testing, Software Maintenance and Configuration Management
  17. Paper 2 | Current Trends & Technologies: Emerging Tech Trends, Approaches to AI, Search Algorithms, Game Playing, Knowledge Representation, Planning, Multi Agent Systems, Fuzzy Sets, Natural Language Processing, Artificial Neural Networks, Genetic Algorithms, Artificial Intelligence, Data Warehousing & Mining, Electronic Data Interchange and E-Commerce, Terms & Abbreviations
  18. Paper 2 | Full Length Mock Tests:
AI summary & chapters

AI Summary

An AI-generated summary of this video lecture.

The video lecture explains how Semaphores solve the Critical Section Problem for n-processes, overcoming the limitations of Peterson's solution which was restricted to two processes. The instructor presents a generic process structure P_i() containing an initial section, a wait operation, a critical section, a signal operation, and a remainder section. He emphasizes that for mutual exclusion, the semaphore is initialized to 1. The lecture then defines semaphores as integer variables accessed only via atomic operations wait(S) and signal(S), historically known as P(S) and V(S). The implementation details of these operations are shown, where wait decrements the value and signal increments it, ensuring synchronization.

Chapters

  1. 0:00 – 2:00 00:00-02:00

    The instructor begins by stating that Peterson's solution is confined to just two processes, whereas general systems require an n-process solution provided by Semaphores. He displays a code block for a process P_i() structured with a While(T) loop. Inside the loop, he lists the Initial Section, wait(s), Critical Section, signal(s), and Remainder Section. He explicitly writes on the board that while solving the Critical Section Problem, the semaphore S is initialized to 1. He writes P_1, P_2, ..., P_n to represent the multiple processes involved.

  2. 2:00 – 5:00 02:00-05:00

    The lecturer details the specific roles of the synchronization primitives within the process code. He points to wait(s) and labels it as the Entry Section (ES), explaining that this is where the process attempts to enter the critical section. He then points to signal(s) and labels it as the Exit Section (ES), indicating where the process releases the resource. He reiterates the initialization S=1 on the board. He discusses how multiple processes P_1 through P_n will contend for the critical section, and the semaphore mechanism ensures that only one process can proceed at a time based on the value of S.

  3. 5:00 – 8:17 05:00-08:17

    The lecture transitions to a slide titled Operation System Solution to formally define Semaphores. The slide states that a semaphore S is a simple integer variable accessed only through two standard atomic operations: wait(S) and signal(S). The instructor notes that wait(S) was originally termed P(S) and signal(S) was V(S). He shows the code definition for wait(S) which includes a while(s<=0); loop followed by s--;, and signal(S) which simply performs s++;. He explains that these operations are atomic, meaning they cannot be interrupted, which is crucial for preventing race conditions in the synchronization logic.

The lesson progresses from identifying the limitations of previous solutions to introducing a robust mechanism for n-process synchronization. By defining the process structure and the atomic nature of semaphore operations, the instructor establishes the foundation for solving the critical section problem. The distinction between the logical structure of the process and the underlying atomic implementation of the semaphore operations is clearly drawn, highlighting how wait and signal manage access to shared resources.

Loading lesson…