OS-Simulation-Java

A multithreaded operating system simulation in Java implementing processor allocation, priority-based scheduling, and safe concurrency using locks and condition variables.

🚀 Overview

This project simulates core behavior of an operating system scheduler, including:

• Process registration with priorities
• Dynamic processor allocation
• Preemptive scheduling
• Blocking and signaling using Condition variables
• Thread-safe operations with ReentrantLock

It’s designed to emulate how an OS might manage limited CPU cores and prioritize tasks while ensuring thread safety and correctness.

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🧠 Features

• ✅ Priority Queues (0–9) for handling processes by urgency
• ✅ Multiple Processors Support (configurable dynamically)
• ✅ Fair Locking using ReentrantLock(true)
• ✅ Condition Variables to block and wake threads efficiently
• ✅ Graceful Handling of process termination and scheduling

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📁 Project Structure

OS-Simulation-Java/
├── OS.java               # Core operating system simulation
├── OS_sim_interface.java# Interface definition (provided)
├── Tests.java            # Suite of unit & functional tests
├── Main.java             # Entry point to run tests
├── README.md             # You are here :)

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🔧 How It Works

• Registering a Process:
  Each process is assigned a unique PID and a priority from 0 (lowest) to 9 (highest).

• Starting a Process:
  If a processor is free, it's immediately assigned. Otherwise, the process is enqueued based on its priority and blocks using Condition.await().

• Scheduling / Terminating:
  Releases the processor, then signals the next-highest priority waiting process.

• Concurrency Management:
  All shared state (queues, assignments) is guarded by a single ReentrantLock, ensuring correctness under multithreading.

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