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