Caching & Performance Interview Questions

Caching in Laravel stores and retrieves data for faster access. Laravel supports multiple cache drivers (file, database, Redis, Memcached) configured in config/cache.php. Caching improves application performance by reducing database queries and computation.

Basic cache operations include Cache::get() to retrieve, Cache::put() to store, Cache::has() to check existence, Cache::forget() to remove items. Also supports Cache::remember() for compute-and-store operations.

Route caching improves routing performance using 'php artisan route:cache'. Creates a single file of compiled routes. Should be used in production. Must be cleared when routes change using route:clear.

Config caching combines all configuration files into single cached file using 'php artisan config:cache'. Improves performance by reducing file loading. Must be cleared when configs change using config:clear.

View caching compiles Blade templates into PHP code. Happens automatically and stored in storage/framework/views. Can be cleared using view:clear. Improves rendering performance.

Database queries can be cached using remember() method on query builder or Eloquent models. Example: User::remember(60)->get(). Also supports tags and cache invalidation strategies.

Cache tags group related items for easy manipulation. Use Cache::tags(['tag'])->put() for storage. Can flush all tagged cache using Cache::tags(['tag'])->flush(). Not all drivers support tagging.

Eager loading reduces N+1 query problems by loading relationships in advance using with() method. Example: User::with('posts')->get(). Improves performance by reducing database queries.

Response caching stores HTTP responses using middleware. Configure using Cache-Control headers. Supports client-side and server-side caching. Improves response times for static content.

Cache keys uniquely identify cached items. Use meaningful names and version prefixes. Handle key collisions. Support cache namespacing. Consider key length limits.

Cache versioning handles cache invalidation using version prefixes in keys. Increment version to invalidate all related cache. Support rolling updates. Handle version migrations.

Distributed caching uses Redis or Memcached across multiple servers. Handle cache synchronization. Support cache replication. Implement fallback strategies. Monitor cache health.

Database optimization includes proper indexing, query optimization, using chunking for large datasets, implementing pagination, optimizing relationships, and monitoring query performance.

Fragment caching stores portions of views. Use @cache directive in Blade. Support time-based expiration. Handle dynamic content. Implement cache tags for fragments.

Cache warming pre-populates cache before needed. Create warming scripts. Handle cache dependencies. Support progressive warming. Implement warming strategies.

Asset optimization includes minification, compression, bundling using Laravel Mix. Configure cache headers. Use CDN integration. Implement lazy loading. Support asset versioning.

Cache policies define caching rules and strategies. Handle cache lifetime. Support conditional caching. Implement cache priorities. Configure cache headers.

Queue optimization improves job processing performance. Configure worker processes. Handle job batching. Implement queue priorities. Monitor queue performance.

Session optimization includes choosing appropriate driver, configuring session lifetime, handling session cleanup, implementing session locking, monitoring session size.

Cache locks prevent race conditions in distributed systems. Use Cache::lock() method. Handle lock timeouts. Implement automatic release. Support lock retries.

Profile application using tools like Laravel Telescope, Clockwork. Monitor performance metrics. Track database queries. Analyze memory usage. Identify bottlenecks.

Cache sharding distributes cache across multiple nodes. Implement shard selection. Handle shard rebalancing. Support shard failover. Monitor shard health.

Hierarchical caching uses multiple cache layers. Implement cache fallback. Handle cache propagation. Support cache invalidation hierarchy. Monitor cache hit rates.

Memory optimization includes monitoring allocations, implementing garbage collection, optimizing data structures, handling memory leaks, configuring PHP memory limits.

Cache events track cache operations. Handle cache hits/misses. Implement cache warming events. Support event listeners. Monitor cache performance.

Load balancing distributes traffic across servers. Configure load balancer. Handle session affinity. Support health checks. Monitor server performance.

API optimization includes implementing rate limiting, caching responses, optimizing serialization, handling pagination, monitoring API metrics.

Cache warm-up strategies include identifying critical data, implementing progressive warming, handling cache dependencies, monitoring warm-up performance.

File system optimization includes caching file operations, implementing proper file handling, optimizing storage operations, monitoring disk usage.

Performance monitoring includes tracking metrics, implementing logging, setting up alerts, analyzing trends, identifying performance issues.