Memory leaks in Node.js are often caused by unclosed database connections or uncollected variables. Profiling tools and garbage collection monitoring can help identify the root cause.

Memory leaks in a Node.js application can manifest as increased memory consumption over time, which eventually leads to app crashes or performance degradation. These leaks are typically caused by unclosed resources, such as open database connections, lingering event listeners, or global variables holding onto data longer than necessary. To tackle memory leaks, start by enabling garbage collection tracking with --expose-gc and taking heap snapshots periodically to analyze which objects are not being garbage collected. Commonly, third-party libraries or misconfigured caching can also contribute to leaks; if a cache isn’t cleared or a library retains a large dataset in memory, this can cause gradual memory accumulation. Using the Chrome DevTools profiler or tools like Clinic.js can reveal which functions or variables are holding onto memory longer than they should. Event listeners that aren’t removed after use can also lead to memory leaks, especially in WebSocket or long-polling connections where frequent communication can cause memory usage to spiral. Refactoring code to minimize the creation of circular references, using weak references where applicable, and periodically clearing stale objects from caches or connections helps reduce memory strain on the application. Regular monitoring and testing with controlled memory loads can help maintain optimal performance while minimizing memory retention over time.