Singleton Pattern Explained: How Backend Devs Prevent Database Crashes

A technical series titled 'The Everyday Backend Engineer: Practical Design Patterns' has launched its first installment focusing on the Singleton Pattern, a creational design pattern widely used in backend development. The pattern addresses a critical problem where spinning up a new database connection per request can exhaust a database's connection limit — often capped around 100 — causing fatal errors and server crashes. The Singleton approach ensures only one shared database connection instance is created at server startup and reused across all modules. In Node.js, this is implemented by leveraging the built-in CommonJS module caching system, which automatically returns the same exported instance on every subsequent import. The article demonstrates a practical Node.js and PostgreSQL implementation using a frozen class instance exported as a shared connection pool.