7.1 KiB
🖥️ Process Scheduler Simulator
An interactive educational tool for visualizing and comparing classical CPU scheduling algorithms from Operating Systems.
✨ What is it?
The Process Scheduler Simulator (PSS) runs entirely in the browser — no server, no system dependencies. You define the processes, choose the algorithm, and watch the simulation unfold in real time through the Gantt chart.
Ideal for:
- 📚 Operating Systems students who want to visualize what was once only theory
- 👩🏫 Instructors looking for an interactive classroom tool
- 🔍 Professionals revisiting OS fundamentals
A live demo is available at: https://pss.lucasrguerra.dev.br/
🚀 Quick Start
Prerequisites
- Node.js 20+
- npm 10+
Local installation and run
# Clone the repository
git clone https://github.com/lucasrguerra/pss.git
cd pss
# Install dependencies
npm install
# Start the development server
npm run dev
Open http://localhost:5173 in your browser.
Production build
npm run build
npm run preview
With Docker
docker compose up
🎮 How to use
- Create your processes — In the left panel, add processes by defining name, arrival time, priority, and a sequence of bursts (CPU and I/O). Or use the random generator to get started quickly.
- Configure the scheduler — Choose an algorithm and adjust the parameters (quantum for RR, aging for Priority, etc.).
- Run the simulation — Use the Play/Pause/Step controls to run the simulation at the speed you want (0.25× to 4×).
- Analyze the results — The Gantt chart shows each process's state in real time. At the end, the metrics panel displays turnaround, waiting time, throughput, and more.
💡 Tip: Load one of the built-in presets to see classic phenomena such as the FCFS convoy effect or priority starvation.
⚙️ Supported Algorithms
| Algorithm | Preemptive? | Parameters |
|---|---|---|
| FCFS — First Come, First Served | ❌ | — |
| SJF — Shortest Job First | ❌ | — |
| SRTF — Shortest Remaining Time First | ✅ | — |
| Round Robin (RR) | ✅ | Quantum |
| Priority NP — Non-Preemptive Priority | ❌ | Aging (optional) |
| Priority P — Preemptive Priority | ✅ | Aging (optional) |
| HRRN — Highest Response Ratio Next | ❌ | — |
| Multilevel Queue | ✅ | Quantum per queue |
See the algorithms documentation for details on how each one works.
📊 Computed Metrics
For each simulated process, PSS automatically computes:
- Response Time — time until the first CPU usage
- Turnaround Time — total time from arrival to completion
- Waiting Time — total time spent in the Ready queue
- CPU Time / I/O Time — effective time in each type of burst
- CPU Utilization — percentage of turnaround time spent on CPU
- Bound Type — automatic classification as CPU Bound, I/O Bound, or Balanced
Globally: averages for response/turnaround/waiting, throughput, and overall CPU utilization.
🗂️ Project Structure
src/
├── core/ # Pure logic — no React
│ ├── algorithms/ # Implementation of each algorithm
│ │ ├── base.ts # Abstract class BaseScheduler
│ │ ├── fcfs.ts
│ │ ├── sjf.ts
│ │ ├── rr.ts
│ │ ├── priority.ts
│ │ ├── priority_rr.ts
│ │ ├── hrrn.ts
│ │ ├── multilevel.ts
│ │ └── index.ts # Dispatch by algorithm
│ ├── engine.ts # SimulationEngine — orchestrates the ticks
│ ├── metrics.ts # Per-process and global metrics computation
│ ├── types.ts # All TypeScript interfaces
│ └── presets.ts # Pre-defined scenarios
│
├── store/ # Global state with Zustand
├── components/ # React components
│ ├── ProcessPanel/ # Process creation and editing
│ ├── SchedulerPanel/ # Algorithm selection and parameters
│ ├── ControlBar/ # Play, Pause, Step, Reset, speed
│ ├── GanttChart/ # Interactive Gantt chart
│ ├── MetricsPanel/ # Table, charts, and global metrics
│ └── shared/ # Buttons, badges, tooltips, modals
│
└── hooks/ # Custom hooks (animation loop, export, etc.)
📦 Available Presets
Load classic scenarios with a single click to explore OS phenomena:
| Preset | What it demonstrates |
|---|---|
classic_fcfs |
Basic execution with FCFS, no I/O |
convoy_effect |
Convoy effect: one long process blocking many short ones |
rr_demo |
Fair time-sharing with Round Robin (quantum=3) |
starvation |
Low-priority processes never receive CPU |
aging_fix |
The same starvation scenario, solved with aging |
io_heavy |
Mix of CPU Bound vs. I/O Bound processes |
multilevel_demo |
Multiple queues with different priorities |
🧪 Tests
# Run all unit tests
npm test
# Watch mode (re-runs on save)
npm run test:watch
# With coverage report
npm run test:coverage
Tests cover the simulation engine, all scheduling algorithms, and metrics computation.
🛠️ Technology Stack
| Layer | Technology |
|---|---|
| UI Framework | React 18 |
| Language | TypeScript 5 |
| Build tool | Vite 6 |
| Styling | Tailwind CSS 4 |
| Global state | Zustand 5 |
| Charts | Recharts |
| Icons | Lucide React |
| Testing | Vitest + Testing Library |
📄 Additional Documentation
- 📐 Scheduling Algorithms — detailed description of each algorithm, tie-breaking rules, and examples
- 📏 Metrics — formulas and definitions for all computed metrics
- 📝 JOSS Paper — scientific paper submitted to the Journal of Open Source Software
Também disponível em: 🇧🇷 Português
🤝 Contributing
Contributions are welcome! Please read our CONTRIBUTING.md guide for details on our code of conduct, and the process for submitting Pull Requests to us.
📜 License
Distributed under the MIT License. Developed by Lucas Rayan Guerra.