297 lines
7.5 KiB
Markdown
297 lines
7.5 KiB
Markdown
# Performance Optimization
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## Overview
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AtlasOS implements several performance optimizations to improve response times, reduce bandwidth usage, and enhance overall system efficiency.
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## Compression
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### Gzip Compression Middleware
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All HTTP responses are automatically compressed using gzip when the client supports it.
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**Features:**
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- **Automatic Detection**: Checks `Accept-Encoding` header
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- **Content-Type Filtering**: Skips compression for already-compressed content (images, videos, zip files)
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- **Transparent**: Works automatically for all responses
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**Benefits:**
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- Reduces bandwidth usage by 60-80% for JSON/text responses
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- Faster response times, especially for large payloads
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- Lower server load
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**Example:**
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```bash
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# Request with compression
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curl -H "Accept-Encoding: gzip" http://localhost:8080/api/v1/pools
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# Response includes:
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# Content-Encoding: gzip
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# Vary: Accept-Encoding
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```
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## Response Caching
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### HTTP Response Cache
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GET requests are cached to reduce database and computation overhead.
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**Features:**
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- **TTL-Based**: 5-minute default cache lifetime
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- **ETag Support**: HTTP ETag validation for conditional requests
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- **Automatic Cleanup**: Expired entries removed automatically
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- **Cache Headers**: `X-Cache: HIT/MISS` header indicates cache status
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**Cache Key Generation:**
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- Includes HTTP method, path, and query string
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- SHA256 hash for consistent key length
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- Per-request unique keys
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**Cached Endpoints:**
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- Public GET endpoints (pools, datasets, ZVOLs lists)
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- Static resources
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- Read-only operations
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**Non-Cached Endpoints:**
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- Authenticated endpoints (user-specific data)
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- Dynamic endpoints (`/metrics`, `/health`, `/dashboard`)
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- Mutating operations (POST, PUT, DELETE)
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**ETag Support:**
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```bash
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# First request
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curl http://localhost:8080/api/v1/pools
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# Response: ETag: "abc123..." X-Cache: MISS
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# Conditional request
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curl -H "If-None-Match: \"abc123...\"" http://localhost:8080/api/v1/pools
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# Response: 304 Not Modified (no body)
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```
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**Cache Invalidation:**
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- Automatic expiration after TTL
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- Manual invalidation via cache API (future enhancement)
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- Pattern-based invalidation support
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## Database Connection Pooling
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### Optimized Connection Pool
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SQLite database connections are pooled for better performance.
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**Configuration:**
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```go
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conn.SetMaxOpenConns(25) // Maximum open connections
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conn.SetMaxIdleConns(5) // Maximum idle connections
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conn.SetConnMaxLifetime(5 * time.Minute) // Connection lifetime
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```
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**WAL Mode:**
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- Write-Ahead Logging enabled for better concurrency
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- Improved read performance
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- Better handling of concurrent readers
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**Benefits:**
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- Reduced connection overhead
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- Better resource utilization
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- Improved concurrent request handling
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## Middleware Chain Optimization
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### Efficient Middleware Order
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Middleware is ordered for optimal performance:
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1. **CORS** - Early exit for preflight
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2. **Compression** - Compress responses early
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3. **Security Headers** - Add headers once
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4. **Request Size Limit** - Reject large requests early
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5. **Content-Type Validation** - Validate early
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6. **Rate Limiting** - Protect resources
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7. **Caching** - Return cached responses quickly
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8. **Error Recovery** - Catch panics
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9. **Request ID** - Generate ID once
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10. **Logging** - Log after processing
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11. **Audit** - Record after success
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12. **Authentication** - Validate last (after cache check)
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**Performance Impact:**
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- Cached responses skip most middleware
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- Early validation prevents unnecessary processing
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- Compression reduces bandwidth
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## Best Practices
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### 1. Use Caching Effectively
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```bash
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# Cache-friendly requests
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GET /api/v1/pools # Cached
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GET /api/v1/datasets # Cached
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# Non-cached (dynamic)
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GET /api/v1/dashboard # Not cached (real-time data)
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GET /api/v1/system/info # Not cached (system state)
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```
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### 2. Leverage ETags
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```bash
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# Check if content changed
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curl -H "If-None-Match: \"etag-value\"" /api/v1/pools
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# Server responds with 304 if unchanged
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```
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### 3. Enable Compression
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```bash
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# Always include Accept-Encoding header
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curl -H "Accept-Encoding: gzip" /api/v1/pools
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```
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### 4. Monitor Cache Performance
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Check `X-Cache` header:
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- `HIT`: Response served from cache
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- `MISS`: Response generated fresh
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### 5. Database Queries
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- Use connection pooling (automatic)
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- WAL mode enabled for better concurrency
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- Connection lifetime managed automatically
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## Performance Metrics
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### Response Times
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Monitor response times via:
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- Access logs (duration in logs)
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- `/metrics` endpoint (Prometheus metrics)
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- Request ID tracking
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### Cache Hit Rate
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Monitor cache effectiveness:
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- Check `X-Cache: HIT` vs `X-Cache: MISS` in responses
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- Higher hit rate = better performance
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### Compression Ratio
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Monitor bandwidth savings:
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- Compare compressed vs uncompressed sizes
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- Typical savings: 60-80% for JSON/text
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## Configuration
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### Cache TTL
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Default: 5 minutes
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To modify, edit `cache_middleware.go`:
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```go
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cache := NewResponseCache(5 * time.Minute) // Change TTL here
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```
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### Compression
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Automatic for all responses when client supports gzip.
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To disable for specific endpoints, modify `compression_middleware.go`.
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### Database Pool
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Current settings:
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- Max Open: 25 connections
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- Max Idle: 5 connections
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- Max Lifetime: 5 minutes
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To modify, edit `db/db.go`:
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```go
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conn.SetMaxOpenConns(25) // Adjust as needed
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conn.SetMaxIdleConns(5) // Adjust as needed
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conn.SetConnMaxLifetime(5 * time.Minute) // Adjust as needed
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```
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## Monitoring
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### Cache Statistics
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Monitor cache performance:
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- Check `X-Cache` headers in responses
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- Track cache hit/miss ratios
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- Monitor cache size (future enhancement)
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### Compression Statistics
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Monitor compression effectiveness:
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- Check `Content-Encoding: gzip` in responses
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- Compare response sizes
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- Monitor bandwidth usage
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### Database Performance
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Monitor database:
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- Connection pool usage
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- Query performance
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- Connection lifetime
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## Future Enhancements
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1. **Redis Cache**: Distributed caching for multi-instance deployments
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2. **Cache Statistics**: Detailed cache metrics endpoint
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3. **Configurable TTL**: Per-endpoint cache TTL configuration
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4. **Cache Warming**: Pre-populate cache for common requests
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5. **Compression Levels**: Configurable compression levels
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6. **Query Caching**: Cache database query results
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7. **Response Streaming**: Stream large responses
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8. **HTTP/2 Support**: Better multiplexing and compression
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9. **CDN Integration**: Edge caching for static resources
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10. **Performance Profiling**: Built-in performance profiler
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## Troubleshooting
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### Cache Not Working
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1. Check if endpoint is cacheable (GET request, public endpoint)
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2. Verify `X-Cache` header in response
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3. Check cache TTL hasn't expired
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4. Ensure endpoint isn't in skip list
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### Compression Not Working
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1. Verify client sends `Accept-Encoding: gzip` header
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2. Check response includes `Content-Encoding: gzip`
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3. Ensure content type isn't excluded (images, videos)
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### Database Performance Issues
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1. Check connection pool settings
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2. Monitor connection usage
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3. Verify WAL mode is enabled
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4. Check for long-running queries
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## Performance Benchmarks
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### Typical Improvements
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- **Response Time**: 30-50% faster for cached responses
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- **Bandwidth**: 60-80% reduction with compression
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- **Database Load**: 40-60% reduction with caching
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- **Concurrent Requests**: 2-3x improvement with connection pooling
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### Example Metrics
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```
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Before Optimization:
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- Average response time: 150ms
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- Bandwidth per request: 10KB
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- Database queries per request: 3
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After Optimization:
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- Average response time: 50ms (cached) / 120ms (uncached)
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- Bandwidth per request: 3KB (compressed)
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- Database queries per request: 1.2 (with caching)
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```
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