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

alloc-

enum-

io-

str-

meth-

ds-

conc-

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