Elixir Performance Review

Quick Reference

Issue Type Reference

Mailbox overflow, blocking calls references/genserver-bottlenecks.md

When to use ETS, read/write concurrency references/ets-patterns.md

Binary handling, large messages references/memory.md

Task patterns, flow control references/concurrency.md

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

Issue Flag ONLY IF

GenServer bottleneck Handles > 1000 req/sec OR blocking I/O in callbacks

Use streams Processing > 10k items OR reading large files

Use ETS Read:write ratio > 10:1 AND concurrent access

Before Submitting Findings

Load and follow review-verification-protocol before reporting any issue.