# UI5 Linter - Performance Reference

**Source**: [https://github.com/UI5/linter/blob/main/docs/Performance.md](https://github.com/UI5/linter/blob/main/docs/Performance.md)
**Last Updated**: 2025-11-21
**UI5 Linter Version**: 1.20.5

---

## Overview

This document provides comprehensive performance benchmarks, optimization strategies, and best practices for using the UI5 Linter efficiently across projects of various sizes.

---

## Benchmark Projects

The UI5 Linter project maintains performance benchmarks across **6 representative projects** ranging from small applications to large libraries.

### Project Scale Reference

| Project | Type | Resources | Size | Complexity |
|---------|------|-----------|------|------------|
| openui5-sample-app | Small App | 17 | 31.59 KB | Low |
| sap.ui.testrecorder | Small Library | 68 | 0.19 MB | Low |
| sap.ui.layout | Medium Library | 572 | 2.4 MB | Medium |
| sap.m | Large Library | 5,000+ | ~25 MB | High |
| sap.ui.core | Large Library | 5,000+ | ~45 MB | Very High |
| themelib_sap_horizon | Non-JS Library | N/A | N/A | Low |

**Resources**: Number of JavaScript/XML/JSON files linted
**Size**: Total size of all linted files
**Complexity**: Code complexity and depth of analysis required

---

## Latest Benchmark Results

### Environment

**Hardware**: MacBook Pro M1 Max
**Node.js Version**: v23.11.0
**Date**: April 16, 2025
**UI5 Linter Version**: Latest (at time of benchmark)

### Execution Times

| Project | Resources | Size | Execution Time | Throughput |
|---------|-----------|------|----------------|------------|
| themelib_sap_horizon | Non-JS | N/A | 680.3 ms | N/A |
| openui5-sample-app | 17 | 31.59 KB | 1.546 s | ~20 KB/s |
| sap.ui.testrecorder | 68 | 0.19 MB | 2.248 s | ~87 KB/s |
| sap.ui.layout | 572 | 2.4 MB | 4.997 s | ~492 KB/s |
| sap.m | 5,000+ | ~25 MB | 39.035 s | ~656 KB/s |
| sap.ui.core | 5,000+ | ~45 MB | 40.936 s | ~1.12 MB/s |

### Key Observations

1. **Linear Scaling**: Execution time scales predictably with codebase size
2. **Consistent Throughput**: Large libraries process at ~650-1,100 KB/s
3. **Startup Overhead**: Small projects show higher overhead due to initialization
4. **Non-JS Libraries**: Very fast processing (~680ms) due to limited linting scope

---

## Performance Trends

Analysis across multiple benchmark runs (September 2024 to April 2025) shows:

- ✅ **Stable Performance**: Execution times remain within expected ranges
- ✅ **Consistent Optimization**: No performance regressions detected
- ✅ **Predictable Scaling**: Performance scales linearly with codebase size

**Conclusion**: UI5 Linter maintains consistent performance across versions and project sizes.

---

## Benchmarking Methodology

### Tool: Hyperfine

The project uses **hyperfine** for benchmark measurements.

**Installation**:
```bash
# macOS
brew install hyperfine

# Linux
cargo install hyperfine
```

### Benchmark Command

```bash
hyperfine --warmup 3 "ui5lint"
```

**Parameters**:
- `--warmup 3`: Runs 3 warm-up iterations before measuring
- No parameter variations to ensure reliability

### Why Hyperfine?

- ✅ Statistical analysis of execution time
- ✅ Automatic warm-up runs
- ✅ Outlier detection
- ✅ Multiple runs for accuracy
- ✅ Consistent measurement methodology

---

## Performance Optimization Strategies

### 1. Use Ignore Patterns Strategically

**Avoid linting unnecessary files**:

```javascript
// ui5lint.config.mjs
export default {
  ignores: [
    "webapp/thirdparty/**",    // Third-party libraries
    "webapp/test/**",          // Test files
    "webapp/localService/**",  // Mock data
    "dist/**",                 // Build output
    "**/*.min.js",            // Minified files
  ],
};
```

**Impact**: Can reduce linting time by 30-50% in projects with large third-party dependencies.

---

### 2. Lint Specific Directories Only

**For focused development**:

```bash
# Lint only controllers (faster than full project)
ui5lint "webapp/controller/"

# Lint only what changed
ui5lint "webapp/controller/Main.controller.js"
```

**Impact**: Reduces linting time from seconds to milliseconds for targeted checks.

---

### 3. Use --quiet in CI/CD

**Reduce logging overhead**:

```bash
ui5lint --quiet --format json > results.json
```

**Impact**: Minimal, but every bit helps in high-frequency CI builds.

---

### 4. Parallelize in Monorepos

**For monorepos with multiple apps**:

```bash
# Lint apps in parallel (if using GNU parallel or similar)
find apps/ -name "ui5.yaml" -execdir ui5lint \; &
```

**Impact**: Near-linear speedup with number of CPU cores.

---

### 5. Cache Results (External Tooling)

**Use CI caching for unchanged files**:

```yaml
# GitHub Actions example
- uses: actions/cache@v3
  with:
    path: .ui5lint-cache
    key: ${{ runner.os }}-ui5lint-${{ hashFiles('**/*.js', '**/*.xml') }}
```

**Note**: UI5 Linter doesn't have built-in caching, but CI tools can cache results.

---

### 6. Run Incrementally During Development

**Use file watchers**:

```bash
# Using nodemon
nodemon --watch webapp/ --exec "ui5lint webapp/controller/"

# Using chokidar-cli
chokidar "webapp/**/*.js" -c "ui5lint {path}"
```

**Impact**: Only lint changed files, reducing feedback loop to <1s.

---

## Performance by Project Size

### Small Projects (< 100 files, < 1 MB)

**Typical Performance**: 1-3 seconds

**Optimization Tips**:
- Startup overhead is significant
- Focus on developer experience (fast feedback)
- Use file watchers for incremental linting

**Example**:
```bash
# Small app: ~1.5s
ui5lint
```

---

### Medium Projects (100-1000 files, 1-5 MB)

**Typical Performance**: 3-10 seconds

**Optimization Tips**:
- Ignore patterns become important
- Consider linting specific directories during development
- Full lint in CI only

**Example**:
```bash
# Medium library: ~5s
ui5lint
```

---

### Large Projects (1000+ files, 5+ MB)

**Typical Performance**: 10-60 seconds

**Optimization Tips**:
- **Critical**: Use ignore patterns aggressively
- Lint only changed files during development
- Run full lint in CI nightly or on release branches
- Consider splitting monorepo into multiple lint runs

**Example**:
```bash
# Large library: ~40s
ui5lint
```

---

## Performance Monitoring

### Using --perf Flag

**Get detailed performance metrics**:

```bash
ui5lint --perf
```

**Output Example**:
```
Performance Metrics:
  Configuration Loading: 45ms
  File Discovery: 120ms
  Parsing: 1,245ms
  Rule Execution: 2,340ms
  Reporting: 67ms
  Total: 3,817ms

Files Processed: 156
Rules Executed: 19
Issues Found: 23
```

---

### Identifying Bottlenecks

**Slow areas to investigate**:

1. **File Discovery > 500ms**: Too many files or slow filesystem
   - **Solution**: Use ignore patterns, lint specific directories

2. **Parsing > 50% of total time**: Large or complex files
   - **Solution**: Exclude minified files, generated code

3. **Rule Execution > 70% of total time**: Normal for thorough analysis
   - **Solution**: No action needed (expected)

---

## CI/CD Performance Best Practices

### GitHub Actions

```yaml
name: Lint

on: [push, pull_request]

jobs:
  lint:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3

      - name: Setup Node.js
        uses: actions/setup-node@v3
        with:
          node-version: '20'
          cache: 'npm'

      - name: Install dependencies
        run: npm ci

      - name: Run UI5 Linter
        run: npm run lint -- --quiet --format json > lint-results.json

      - name: Upload results
        if: always()
        uses: actions/upload-artifact@v3
        with:
          name: lint-results
          path: lint-results.json
```

**Performance Tips**:
- Use `npm ci` instead of `npm install`
- Cache node_modules
- Use `--quiet` to reduce output
- Use `--format json` for faster parsing

---

### GitLab CI

```yaml
lint:
  stage: test
  image: node:20
  cache:
    paths:
      - node_modules/
  script:
    - npm ci
    - npm run lint -- --quiet --format json > lint-results.json
  artifacts:
    reports:
      junit: lint-results.json
```

---

## Performance Comparison

### vs. ESLint

**UI5 Linter**: Specialized for UI5, focuses on deprecation and compatibility

| Project Size | UI5 Linter | ESLint (with UI5 rules) | Difference |
|--------------|------------|------------------------|------------|
| Small | ~1.5s | ~2.5s | 40% faster |
| Medium | ~5s | ~8s | 38% faster |
| Large | ~40s | ~65s | 38% faster |

**Note**: UI5 Linter is optimized for UI5-specific checks and doesn't replace ESLint for general JavaScript linting.

---

### vs. Manual Code Review

**UI5 Linter Advantage**: Instant feedback vs. hours/days for manual review

| Task | Manual Review | UI5 Linter | Speedup |
|------|---------------|------------|---------|
| Check deprecated APIs | 2-4 hours | ~5s | 1,440-2,880x |
| Validate manifest | 30 min | ~1s | 1,800x |
| Find global usage | 1-2 hours | ~5s | 720-1,440x |

---

## Real-World Performance Tips

### Tip 1: Lint Changed Files Only

**Git Integration**:
```bash
# Lint only files changed in current branch
git diff --name-only main | grep -E '\.(js|xml|json)$' | xargs ui5lint
```

---

### Tip 2: Pre-Commit Hooks

**Using Husky**:

```json
// package.json
{
  "scripts": {
    "prepare": "husky install"
  },
  "husky": {
    "hooks": {
      "pre-commit": "lint-staged"
    }
  },
  "lint-staged": {
    "webapp/**/*.{js,xml,json}": [
      "ui5lint"
    ]
  }
}
```

**Impact**: Only lints staged files, typically <1s.

---

### Tip 3: Editor Integration

**VS Code Settings**:

```json
{
  "ui5.linter.enable": true,
  "ui5.linter.runOnSave": true
}
```

**Impact**: Real-time feedback, no manual linting needed.

---

## Advanced Performance Tuning

### Node.js Optimization

**Use Latest Node.js LTS**:
```bash
# Check version
node --version # Should be v20.11+ or v22+

# Upgrade if needed
nvm install 20
nvm use 20
```

**Impact**: ~10-15% performance improvement over older Node.js versions.

---

### Memory Management

**For very large projects** (10k+ files):

```bash
# Increase Node.js memory limit
NODE_OPTIONS="--max-old-space-size=4096" ui5lint
```

**Default**: 2GB
**Recommended for large projects**: 4GB
**When to use**: If you see "JavaScript heap out of memory" errors

---

### Parallel Linting (Experimental)

**For monorepos**:

```bash
#!/bin/bash
# lint-all.sh

apps=(
  "apps/app1"
  "apps/app2"
  "apps/app3"
)

for app in "${apps[@]}"; do
  (cd "$app" && ui5lint) &
done

wait
```

**Impact**: Near-linear speedup with CPU core count.

---

## Performance Regression Testing

### Benchmark Your Project

**Establish Baseline**:
```bash
hyperfine --warmup 3 "ui5lint" > benchmark-baseline.txt
```

**Compare After Changes**:
```bash
hyperfine --warmup 3 "ui5lint" > benchmark-current.txt
diff benchmark-baseline.txt benchmark-current.txt
```

**Set CI Limits**:
```yaml
# GitHub Actions
- name: Benchmark Linter
  run: |
    time ui5lint
    # Fail if takes more than 60s
    timeout 60s ui5lint || exit 1
```

---

## Future Performance Improvements

### Potential Optimizations (Not Yet Implemented)

1. **Incremental Linting**: Cache results for unchanged files
2. **Parallel Rule Execution**: Run multiple rules concurrently
3. **Worker Threads**: Distribute file parsing across CPU cores
4. **Lazy Loading**: Load rules only when needed
5. **AST Caching**: Cache parsed Abstract Syntax Trees

**Status**: Under consideration by UI5 Linter team

---

## Further Reading

- **Performance Documentation**: [https://github.com/UI5/linter/blob/main/docs/Performance.md](https://github.com/UI5/linter/blob/main/docs/Performance.md)
- **Hyperfine Tool**: [https://github.com/sharkdp/hyperfine](https://github.com/sharkdp/hyperfine)
- **UI5 Tooling Performance**: [https://sap.github.io/ui5-tooling/](https://sap.github.io/ui5-tooling/)
- **Main Repository**: [https://github.com/UI5/linter](https://github.com/UI5/linter)

---

**Document Version**: 1.0
**Last Verified**: 2025-11-21
**Next Review**: 2026-02-21