The cluster module enables creating child processes that share server ports, allowing Node.js applications to utilize multiple CPU cores.
Basic Setup
Loading code block...
Worker Management
Loading code block...
Auto-Restart Workers
Loading code block...
Graceful Shutdown
Loading code block...
Inter-Process Communication
Loading code block...
Load Balancing
Loading code block...
Zero-Downtime Restart
Loading code block...
Shared State with External Store
Loading code block...
Worker Health Checks
Loading code block...
Best Practices
Setup:
✓ Fork based on CPU count
✓ Implement auto-restart
✓ Handle graceful shutdown
✓ Use external state storage
Communication:
✓ Keep messages small
✓ Use structured message types
✓ Handle message errors
✓ Implement timeouts
Reliability:
✓ Health checks
✓ Zero-downtime restarts
✓ Crash recovery
✓ Resource limits
Avoid:
✗ Sharing memory between workers
✗ Too many workers
✗ Ignoring worker crashes
✗ Long-running synchronous code
Conclusion
The cluster module enables horizontal scaling by utilizing multiple CPU cores. The primary process manages worker processes that share server ports. Implement auto-restart for crashed workers, graceful shutdown for deployments, and health checks for reliability. Use external stores like Redis for shared state since workers have separate memory spaces. For production, consider process managers like PM2 that handle clustering automatically.