elixir-performance-review

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.