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

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