Memory Leak in Node.js: Increasing Heap Memory and Performance Degradation

My Node.js service’s heap usage climbs steadily over time, CPU becomes unresponsive, and eventually crashes with “JavaScript heap out of memory”. How do I detect, debug, and fix such memory leaks?

Memory leaks happen when references to unused objects are retained, preventing garbage collection. Common culprits include unremoved event listeners, lingering timers, global variables, and closures holding large objectsDEV Community+9Better Stack+9DEV Community+9.

🛠️ Steps to Diagnose and Fix: 🔍 1. Monitor Memory Growth Log periodic stats using: js CopyEdit setInterval(() => { const { heapUsed } = process.memoryUsage(); console.log(Heap used: ${(heapUsed / 1024 / 1024).toFixed(2)} MB); }, 5000); If memory keeps growing even without increasing load, that's a leakHowik+2DEV Community+2coderkiran.com+2. 🔬 2. Use Profiling Tools • Run Node with --inspect and capture heap snapshots. • Use tools like Clinic.js, Chrome DevTools, or heapdump to examine retained objects and growth patternscoderkiran.com+2Codez Up+2InfiniteJS+2Howik+4DEV Community+4Codez Up+4. 🧹 3. Identify Common Leak Sources: • Event Listeners / Timers: Remove them with .off(), clearTimeout(), or clearInterval(). • Global Variables: Avoid or nullify them to avoid root-scoped retention. • Closures: Avoid long-lived closures capturing large objects unnecessarilyInfiniteJS+2coderkiran.com+2Codez Up+2InfiniteJS+5Better Stack+5habr.com+5. 🧪 4. Fix and Prevent Leaks • Clean up listeners, timers, and intervals after use. • Use weak references or caches with expiry. • Close database connections, file handles, or sockets promptlyCodez Up.

🧩 TL;DR Memory leaks in Node.js often occur from lingering globals, listeners, or closures. Use profiling tools to track heap usage and clean up unused references systematically to maintain performance.

🧷 Suggested Tags: nodejs, memory-leaks, performance, heap, profiling, gc, debugging