Concurrency vs Parallelism in Node.js - Understanding the Event Loop and Worker Threads

Explore Node.js' asynchronous architecture and learn to distinguish between concurrency and parallelism in this 13-minute conference talk from DevConf.CZ 2025. Discover how Node.js efficiently handles thousands of concurrent connections on a single thread while understanding its limitations with CPU-intensive operations. Dive deep into the Event Loop mechanism, examining how microtasks, macrotasks, and asynchronous execution work together to enable non-blocking I/O operations. Learn when to leverage Node's built-in async model versus implementing Worker Threads for CPU-heavy tasks that could block the main thread. Gain insights from real-world examples including API handling and real-time sports data processing to understand practical applications of these concepts. Master performance optimization techniques for high-scale applications by understanding when each approach—concurrency or parallelism—provides the best solution for specific use cases.