# Ruby Optimise

> Community Ruby Best Practices

- Skill: `comeonoliver/ruby-optimise` (Agent Skill)
- Install (CLI): `npx skillmds@latest add comeonoliver/ruby-optimise`
- Raw SKILL.md: https://api.skillmd.com/api/skills/comeonoliver/ruby-optimise/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: ComeOnOliver (https://skillmd.com/u/comeonoliver)
- Updated: 2026-09-21
- Page: https://skillmd.com/skills/comeonoliver/ruby-optimise

---

# 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`](references/alloc-avoid-unnecessary-dup.md) - Avoid Unnecessary Object Duplication
- [`alloc-freeze-constants`](references/alloc-freeze-constants.md) - Freeze Constant Collections
- [`alloc-lazy-initialization`](references/alloc-lazy-initialization.md) - Use Lazy Initialization for Expensive Objects
- [`alloc-avoid-temp-arrays`](references/alloc-avoid-temp-arrays.md) - Avoid Temporary Array Creation
- [`alloc-reuse-buffers`](references/alloc-reuse-buffers.md) - Reuse Buffers in Loops
- [`alloc-avoid-implicit-conversions`](references/alloc-avoid-implicit-conversions.md) - Avoid Repeated Computation in Hot Paths

### 2. Collection & Enumeration (CRITICAL)

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

### 3. I/O & Database (HIGH)

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

### 4. String Handling (HIGH)

- [`str-frozen-literals`](references/str-frozen-literals.md) - Enable Frozen String Literals
- [`str-shovel-over-plus`](references/str-shovel-over-plus.md) - Use Shovel Operator for String Building
- [`str-interpolation-over-concatenation`](references/str-interpolation-over-concatenation.md) - Use String Interpolation Over Concatenation
- [`str-avoid-repeated-gsub`](references/str-avoid-repeated-gsub.md) - Chain gsub Calls into a Single Replacement
- [`str-symbol-for-identifiers`](references/str-symbol-for-identifiers.md) - Use Symbols for Identifiers and Hash Keys

### 5. Method & Dispatch (MEDIUM-HIGH)

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

### 6. Data Structures (MEDIUM)

- [`ds-set-for-membership`](references/ds-set-for-membership.md) - Use Set for Membership Tests
- [`ds-struct-over-openstruct`](references/ds-struct-over-openstruct.md) - Use Struct Over OpenStruct
- [`ds-sort-by-over-sort`](references/ds-sort-by-over-sort.md) - Use sort_by Instead of sort with Block
- [`ds-array-preallocation`](references/ds-array-preallocation.md) - Preallocate Arrays When Size Is Known
- [`ds-hash-default-value`](references/ds-hash-default-value.md) - Use Hash Default Values Instead of Conditional Assignment

### 7. Concurrency (MEDIUM)

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

### 8. Runtime & Configuration (LOW-MEDIUM)

- [`runtime-enable-yjit`](references/runtime-enable-yjit.md) - Enable YJIT for Production
- [`runtime-tune-gc-parameters`](references/runtime-tune-gc-parameters.md) - Tune GC Parameters for Your Workload
- [`runtime-frozen-string-literal-default`](references/runtime-frozen-string-literal-default.md) - Set Frozen String Literal as Project Default
- [`runtime-optimize-require`](references/runtime-optimize-require.md) - Optimize Require Load Order

## How to Use

Read individual reference files for detailed explanations and code examples:

- [Section definitions](references/_sections.md) - Category structure and impact levels
- [Rule template](assets/templates/_template.md) - Template for adding new rules

## Reference Files

| File | Description |
|------|-------------|
| [references/_sections.md](references/_sections.md) | Category definitions and ordering |
| [assets/templates/_template.md](assets/templates/_template.md) | Template for new rules |
| [metadata.json](metadata.json) | Version and reference information |