Elixir Performance Review

Quick Reference

Review Checklist

GenServer

• Not a single-process bottleneck for all requests
• No blocking operations in handle_call/cast
• Proper timeout configuration
• Consider ETS for read-heavy state

Memory

• Large binaries not copied between processes
• Streams used for large data transformations
• No unbounded data accumulation

Concurrency

• Task.Supervisor for dynamic tasks (not raw Task.async)
• No unbounded process spawning
• Proper backpressure for message producers

Database

• Preloading to avoid N+1 queries
• Pagination for large result sets
• Indexes for frequent queries

Valid Patterns (Do NOT Flag)

• Single GenServer for low-throughput - Not all state needs horizontal scaling
• Synchronous calls for critical paths - Consistency may require it
• In-memory state without ETS - ETS has overhead for small state
• Enum over Stream for small collections - Stream overhead not worth it

Context-Sensitive Rules

Before Submitting Findings