memory-leak-analysis-spas skill

Overview

This skill detects, isolates, and helps fix memory leaks in long-running React Single Page Applications. It focuses on profiling heap snapshots, locating detached DOM trees and closure retention cycles, and validating cleanup logic in hooks and unmount lifecycles. The goal is stable memory usage across extended sessions with reproducible reports.

How this skill works

The skill captures and compares heap snapshots to highlight objects that grow or persist unexpectedly, flagging detached DOM nodes and retained closures from event listeners or stale references. It inspects React hook implementations and lifecycle cleanup paths to verify useEffect and unmount handlers run correctly. It can automate repeated navigations and interactions to produce regression-aware memory reports and trace leaks across routing boundaries.

When to use it

• After noticing gradual memory growth during prolonged app use
• When users report performance degradation or increasing tab memory over time
• During regression testing to prevent reintroduced leaks
• Before release of features that hydrate or stream large datasets
• When adding global listeners, singletons, or cross-route caches

Best practices

• Capture baseline and post-interaction heap snapshots and compare diffs
• Instrument components with weak references or debug IDs to spot detached DOM trees
• Ensure every effect that registers listeners or timers returns a cleanup function
• Use profiling during simulated long sessions with realistic navigation patterns
• Automate memory assertions in CI to catch regressions early

Example use cases

• Find a detached DOM tree left by a modal that doesn’t remove event listeners
• Detect a closure in a custom hook retaining large arrays after route changes
• Validate that server-side hydration of large datasets doesn’t leak on client navigation
• Automate a long-session test that asserts stable resident set size across 1,000 route transitions
• Produce before/after heap comparison reports to prove a fix reduced retained memory

FAQ