Node.js

Node runs JavaScript on V8 and delegates many I/O operations to libuv and the operating system.

• The event loop keeps one process efficient for many concurrent I/O-bound requests.
• CPU-heavy work blocks the main thread unless moved to worker threads or another service.
• libuv uses a thread pool for some filesystem, DNS, crypto, and compression work.

Streams process data in chunks so large files and network responses do not need to sit fully in memory.

• Readable streams produce chunks, writable streams consume them, and transform streams modify chunks.
• Backpressure tells producers to slow down when consumers cannot keep up.
• Use pipeline to wire streams together and handle cleanup on errors.

Reliable Node services combine validation, centralized errors, timeouts, logging, and graceful shutdown.

• Validate input at API boundaries and return consistent error shapes.
• Set timeouts for outbound calls and avoid unbounded retries.
• On shutdown, stop accepting new work, finish in-flight requests, and close database connections.