Community Ruby Best Practices

Comprehensive performance optimization guide for Ruby applications, maintained by the community. Contains 42 rules across 8 categories, prioritized by impact to guide automated refactoring and code generation.

When to Apply

Reference these guidelines when:

• Writing new Ruby code or gems
• Optimizing ActiveRecord queries and database access patterns
• Processing large collections or building data pipelines
• Reviewing code for memory bloat and GC pressure
• Configuring Ruby runtime settings for production

Rule Categories by Priority

Priority	Category	Impact	Prefix
1	Object Allocation	CRITICAL	alloc-
2	Collection & Enumeration	CRITICAL	enum-
3	I/O & Database	HIGH	io-
4	String Handling	HIGH	str-
5	Method & Dispatch	MEDIUM-HIGH	meth-
6	Data Structures	MEDIUM	ds-
7	Concurrency	MEDIUM	conc-
8	Runtime & Configuration	LOW-MEDIUM	runtime-

Quick Reference

1. Object Allocation (CRITICAL)

• alloc-avoid-unnecessary-dup - Avoid Unnecessary Object Duplication
• alloc-freeze-constants - Freeze Constant Collections
• alloc-lazy-initialization - Use Lazy Initialization for Expensive Objects
• alloc-avoid-temp-arrays - Avoid Temporary Array Creation
• alloc-reuse-buffers - Reuse Buffers in Loops
• alloc-avoid-implicit-conversions - Avoid Repeated Computation in Hot Paths

2. Collection & Enumeration (CRITICAL)

• enum-single-pass - Use Single-Pass Collection Transforms
• enum-lazy-large-collections - Use Lazy Enumerators for Large Collections
• enum-flat-map - Use flat_map Instead of map.flatten
• enum-each-with-object - Use each_with_object Over inject for Building Collections
• enum-avoid-count-in-loops - Avoid Recomputing Collection Size in Conditions
• enum-chunk-batch-processing - Use each_slice for Batch Processing

3. I/O & Database (HIGH)

• io-eager-load-associations - Eager Load ActiveRecord Associations
• io-select-only-needed-columns - Select Only Needed Columns
• io-batch-find-each - Use find_each for Large Record Sets
• io-avoid-queries-in-loops - Avoid Database Queries Inside Loops
• io-stream-large-files - Stream Large Files Line by Line
• io-connection-pool-sizing - Size Connection Pools to Match Thread Count
• io-cache-expensive-queries - Cache Expensive Database Results

4. String Handling (HIGH)

• str-frozen-literals - Enable Frozen String Literals
• str-shovel-over-plus - Use Shovel Operator for String Building
• str-interpolation-over-concatenation - Use String Interpolation Over Concatenation
• str-avoid-repeated-gsub - Chain gsub Calls into a Single Replacement
• str-symbol-for-identifiers - Use Symbols for Identifiers and Hash Keys

5. Method & Dispatch (MEDIUM-HIGH)

• meth-avoid-method-missing-hot-paths - Avoid method_missing in Hot Paths
• meth-cache-method-references - Cache Method References for Repeated Calls
• meth-block-vs-proc - Pass Blocks Directly Instead of Converting to Proc
• meth-avoid-dynamic-send - Avoid Dynamic send in Performance-Critical Code
• meth-reduce-method-chain-depth - Reduce Method Chain Depth in Hot Loops

6. Data Structures (MEDIUM)

• ds-set-for-membership - Use Set for Membership Tests
• ds-struct-over-openstruct - Use Struct Over OpenStruct
• ds-sort-by-over-sort - Use sort_by Instead of sort with Block
• ds-array-preallocation - Preallocate Arrays When Size Is Known
• ds-hash-default-value - Use Hash Default Values Instead of Conditional Assignment

7. Concurrency (MEDIUM)

• conc-fiber-for-io - Use Fibers for I/O-Bound Concurrency
• conc-thread-pool-sizing - Size Thread Pools to Match Workload
• conc-ractor-cpu-bound - Use Ractors for CPU-Bound Parallelism
• conc-avoid-shared-mutable-state - Avoid Shared Mutable State Between Threads

8. Runtime & Configuration (LOW-MEDIUM)

• runtime-enable-yjit - Enable YJIT for Production
• runtime-tune-gc-parameters - Tune GC Parameters for Your Workload
• runtime-frozen-string-literal-default - Set Frozen String Literal as Project Default
• runtime-optimize-require - Optimize Require Load Order

How to Use

Read individual reference files for detailed explanations and code examples:

• Section definitions - Category structure and impact levels
• Rule template - Template for adding new rules

Reference Files

File	Description
references/_sections.md	Category definitions and ordering
assets/templates/_template.md	Template for new rules
metadata.json	Version and reference information