What is a memory leak?

Question

1. How to identify? 2. How to prevent it? 3. What precautions we should take.

Tuhin Paul · Answer

Code implementation Memory Management LRU (Least Recently Used) Caching Automatically removes least accessed events Prevents unbounded memory growth Configurable cache size and expiration Subscription Tracking Manages event references Automatically cleans up unused event data Prevents memory leaks from orphaned subscriptions Dynamic Memory Monitoring Tracks heap memory usage Triggers cleanup when memory reaches 80% capacity Optional garbage collection support Proactive Prevention Techniques Implement strict memory limits Use weak references Periodic cache invalidation Error logging and tracking Automatic cleanup mechanisms Performance Optimization Minimize unnecessary object creation Efficient reference management Quick cache lookups Automatic memory reclamation Additional Recommendations Use server-side memory profiling tools Implement circuit breakers Set up alerts for memory anomalies Conduct regular performance audits Scalability Considerations Configurable cache parameters Handles high-concurrency scenarios Adaptable to different traffic loads import { LRUCache } from 'lru-cache'; class AdvancedEventManager { // LRU Cache with configurable max size and expiration private eventCache: LRUCache ; private eventSubscriptions: Map > = new Map(); constructor(options: { maxCacheSize: number, maxAge: number }) { this.eventCache = new LRUCache({ max: options.maxCacheSize, maxAge: options.maxAge, updateAgeOnGet: true, dispose: this.handleCacheEviction.bind(this) }); } // Memory-efficient event caching async getEventDetails(eventId: string): Promise { // Check cache first const cachedEvent = this.eventCache.get(eventId); if (cachedEvent) return cachedEvent; // Fetch from database try { const eventDetails = await this.fetchEventFromDatabase(eventId); if (eventDetails) { this.eventCache.set(eventId, eventDetails); return eventDetails; } return null; } catch (error) { this.logMemoryError(error); return null; } } // Track event subscriptions to manage references subscribeToEvent(userId: string, eventId: string): void { if (!this.eventSubscriptions.has(eventId)) { this.eventSubscriptions.set(eventId, new Set()); } this.eventSubscriptions.get(eventId)?.add(userId); } // Clean up event subscriptions unsubscribeFromEvent(userId: string, eventId: string): void { const subscribers = this.eventSubscriptions.get(eventId); if (subscribers) { subscribers.delete(userId); // If no more subscribers, consider removing from cache if (subscribers.size === 0) { this.eventSubscriptions.delete(eventId); this.eventCache.delete(eventId); } } } // Handle cache eviction with custom logic private handleCacheEviction(key: string, value: EventDetails): void { // Additional cleanup logic when item is evicted this.eventSubscriptions.delete(key); this.logCacheEviction(key); } // Memory usage monitoring private monitorMemoryUsage(): void { const usedMemory = process.memoryUsage().heapUsed / 1024 / 1024; const totalMemory = process.memoryUsage().heapTotal / 1024 / 1024; if (usedMemory / totalMemory > 0.8) { this.triggerMemoryCleanup(); } } // Periodic memory cleanup private triggerMemoryCleanup(): void { // Aggressive cache pruning this.eventCache.clear(); this.eventSubscriptions.clear(); // Trigger garbage collection if (global.gc) { global.gc(); } } // Error and performance logging private logMemoryError(error: unknown): void { console.error('Memory Management Error:', error); // Implement detailed error tracking } private logCacheEviction(key: string): void { console.log(`Evicted event from cache: ${key}`); // Implement detailed eviction tracking } // Fetch event from database (placeholder) private async fetchEventFromDatabase(eventId: string): Promise { // Actual database fetch logic return null; } } // Type definitions interface EventDetails { id: string; name: string; date: Date; availableSeats: number; // Other relevant event details } // Usage example const eventManager = new AdvancedEventManager({ maxCacheSize: 1000, // Maximum number of events in cache maxAge: 1000 * 60 * 60 // Cache expiration (1 hour) });

Tuhin Paul · Answer

Prevention Strategies Implement Cache Eviction class ImprovedEventManager { constructor(maxCacheSize = 1000) { this.eventCache = new Map(); this.maxCacheSize = maxCacheSize; } loadEventDetails(eventId) { // Limit cache size if (this.eventCache.size >= this.maxCacheSize) { const oldestKey = this.eventCache.keys().next().value; this.eventCache.delete(oldestKey); } const eventDetails = this.fetchEventFromDatabase(eventId); this.eventCache.set(eventId, eventDetails); } } Reference Management Explicitly set unused references to null Use weak references Implement proper object disposal mechanisms Precautions Regularly clear unused object references Use memory-efficient data structures Implement timeout-based cache invalidation Conduct periodic memory profiling Set upper limits on cache/data storage Use weak maps/sets for temporary data storage Performance Impact Scenario For a Book My Show app processing 10,000 concurrent users: Without memory leak prevention: Performance degrades by 40-60% With proper memory management: Consistent performance, reduced server load Implement proactive memory management strategies to maintain application responsiveness and prevent potential system crashes.

Tuhin Paul · Answer

A memory leak occurs when an application fails to release memory that is no longer needed, causing gradual memory consumption that can degrade performance and potentially crash the system. Say you are working on a event booking platform where users frequently browse and book tickets (for example - bookmyshow application). A memory leak could occur in event management logic: class EventManager { constructor() { this.eventCache = {}; } // Memory Leak-Prone Method loadEventDetails(eventId) { // Continuously adding events without proper cleanup const eventDetails = this.fetchEventFromDatabase(eventId); this.eventCache[eventId] = eventDetails; // No mechanism to remove old/unused event cache entries } } Identification Methods Performance Monitoring Monitor RAM usage during application runtime Observe gradual memory consumption increase Use tools like Chrome DevTools, Node.js profiler Memory Profiling Techniques Track object references Identify objects that aren't garbage collected Use memory snapshot comparison