Debug Memory Leak Workflow

This workflow helps identify and debug memory leaks in the Cloudflare Workers application.

Steps

1. Enable Memory Debugging
   • Add memory tracking to the worker
   • Enable detailed logging for memory usage
   • Set up memory profiling hooks
2. Collect Memory Metrics

   # Check current memory usage patterns
   wrangler tail --format=json | jq '.event' | grep -i memory

3. Analyze Heap Usage
   • Review object allocation patterns
   • Check for unclosed connections or uncached data
   • Identify long-lived objects that should be garbage collected
4. Common Memory Leak Sources
   • Durable Objects: Check for unclosed WebSocket connections
   • KV Storage: Verify proper cleanup of large values
   • Caches: Ensure cache size limits are enforced
   • Async Operations: Confirm all futures are properly awaited
5. Debugging Commands

   # Monitor memory usage over time
   wrangler tail --format=pretty | grep "Memory usage"
   
   # Check for hanging promises
   wrangler tail --format=json | jq '.log[] | select(.message | contains("promise"))'

6. Fix Common Issues
   • Add explicit cleanup in Durable Object close() methods
   • Implement cache eviction policies
   • Use weak references where appropriate
   • Ensure proper error handling to prevent resource leaks
7. Validate Fixes
   • Run load tests with memory monitoring
   • Verify memory usage stabilizes after garbage collection
   • Check for memory growth under sustained load

Tips

• Use console.log with memory usage timestamps
• Monitor Durable Object lifecycle closely
• Check for event listener leaks
• Review async/await patterns for unresolved promises
• Use WeakMap or WeakSet for temporary object storage

Related Files

• src/lib.rs - Main worker entry point
• src/durable_objects/ - Durable Object implementations
• src/services/cache.rs - Cache management
• src/middleware/ - Request/response handling