How does Rspack's performance monitoring and debugging work?

Rspack's performance monitoring and debugging features are crucial for optimizing the build process and resolving build issues. Here's a detailed explanation of Rspack's performance monitoring and debugging:

Performance Monitoring Tools

1. Build Time Analysis

Use --profile parameter to analyze build time:

bash
npx rspack build --profile --json > stats.json

2. Bundle Analyzer

Use Bundle Analyzer to analyze build results:

javascript
const { BundleAnalyzerPlugin } = require('webpack-bundle-analyzer');

module.exports = {
  plugins: [
    new BundleAnalyzerPlugin({
      analyzerMode: 'static',
      openAnalyzer: false,
      reportFilename: 'bundle-report.html',
      generateStatsFile: true,
      statsFilename: 'stats.json'
    })
  ]
}

3. Build Statistics

Configure detailed build statistics:

javascript
module.exports = {
  stats: {
    colors: true,
    hash: true,
    version: true,
    timings: true,
    assets: true,
    chunks: true,
    modules: true,
    reasons: true,
    children: true,
    source: false,
    errors: true,
    errorDetails: true,
    warnings: true,
    publicPath: true
  }
}

Performance Metrics

1. Build Time

Monitor total build time and time for each phase:

javascript
module.exports = {
  stats: {
    timings: true,
    builtAt: true
  }
}

2. Module Count

Monitor number of modules built:

javascript
module.exports = {
  stats: {
    modules: true,
    chunks: true
  }
}

3. Asset Size

Monitor size of output assets:

javascript
module.exports = {
  stats: {
    assets: true,
    assetsSort: 'size'
  }
}

Debugging Tools

1. Source Map

Configure Source Map for debugging:

javascript
module.exports = {
  mode: 'development',
  devtool: 'eval-cheap-module-source-map'
}

2. Error Overlay

Display error overlay in dev server:

javascript
module.exports = {
  devServer: {
    client: {
      overlay: {
        errors: true,
        warnings: false
      }
    }
  }
}

3. Log Output

Configure log output level:

javascript
module.exports = {
  stats: {
    logging: 'warn',
    loggingDebug: /rspack/
  }
}

Performance Optimization Analysis

1. Module Dependency Analysis

Analyze module dependencies:

javascript
const { DependencyAnalysisPlugin } = require('@rspack/core');

module.exports = {
  plugins: [
    new DependencyAnalysisPlugin({
      filename: 'dependency-analysis.json'
    })
  ]
}

2. Cache Effect Analysis

Analyze cache usage effectiveness:

javascript
module.exports = {
  cache: {
    type: 'filesystem',
    profile: true
  },
  stats: {
    cached: true,
    cachedAssets: true
  }
}

3. Loader Performance Analysis

Analyze Loader execution time:

javascript
const { LoaderOptionsPlugin } = require('@rspack/core');

module.exports = {
  plugins: [
    new LoaderOptionsPlugin({
      debug: true
    })
  ]
}

Common Performance Issues

1. Slow Build Speed

Cause Analysis:

• Cache not enabled
• Long module resolution paths
• Improper Loader configuration
• Too many third-party libraries

Solutions:

javascript
module.exports = {
  cache: {
    type: 'filesystem'
  },
  resolve: {
    modules: [path.resolve(__dirname, 'src'), 'node_modules'],
    extensions: ['.js', '.jsx', '.ts', '.tsx']
  },
  module: {
    rules: [
      {
        test: /\.js$/,
        exclude: /node_modules/,
        use: 'babel-loader'
      }
    ]
  }
}

2. High Memory Usage

Cause Analysis:

• Improper Source Map configuration
• Large file processing
• Too high parallelism

Solutions:

javascript
module.exports = {
  devtool: 'eval-cheap-source-map',
  parallelism: 4,
  optimization: {
    removeAvailableModules: false,
    removeEmptyChunks: false
  }
}

3. Large Bundle Size

Cause Analysis:

• Tree Shaking not used
• Improper code splitting
• Unoptimized third-party libraries

Solutions:

javascript
module.exports = {
  optimization: {
    usedExports: true,
    sideEffects: true,
    splitChunks: {
      chunks: 'all',
      cacheGroups: {
        vendors: {
          test: /[\\/]node_modules[\\/]/,
          priority: -10
        }
      }
    }
  }
}

Performance Monitoring Best Practices

1. Regular Analysis

Regularly analyze build performance:

javascript
// scripts/analyze.js
const { execSync } = require('child_process');
const fs = require('fs');

function analyzeBuild() {
  const startTime = Date.now();
  
  execSync('npx rspack build --profile --json > stats.json');
  
  const endTime = Date.now();
  const duration = endTime - startTime;
  
  console.log(`Build time: ${duration}ms`);
  
  const stats = JSON.parse(fs.readFileSync('stats.json', 'utf8'));
  console.log(`Modules: ${stats.modules.length}`);
  console.log(`Assets: ${stats.assets.length}`);
}

analyzeBuild();

2. Performance Benchmarking

Establish performance benchmarks:

javascript
// scripts/benchmark.js
const { execSync } = require('child_process');

function benchmark() {
  const iterations = 5;
  const times = [];
  
  for (let i = 0; i < iterations; i++) {
    const startTime = Date.now();
    execSync('npx rspack build');
    const endTime = Date.now();
    times.push(endTime - startTime);
  }
  
  const avgTime = times.reduce((a, b) => a + b, 0) / iterations;
  const minTime = Math.min(...times);
  const maxTime = Math.max(...times);
  
  console.log(`Average: ${avgTime}ms`);
  console.log(`Min: ${minTime}ms`);
  console.log(`Max: ${maxTime}ms`);
}

benchmark();

3. Performance Reports

Generate performance reports:

javascript
// scripts/performance-report.js
const fs = require('fs');
const path = require('path');

function generateReport(stats) {
  const report = {
    timestamp: new Date().toISOString(),
    buildTime: stats.time,
    modules: stats.modules.length,
    assets: stats.assets.map(asset => ({
      name: asset.name,
      size: asset.size
    })),
    warnings: stats.warnings.length,
    errors: stats.errors.length
  };
  
  fs.writeFileSync(
    path.join(__dirname, 'performance-report.json'),
    JSON.stringify(report, null, 2)
  );
}

Debugging Techniques

1. Step-by-step Debugging

Enable features gradually to locate issues:

javascript
// 1. Minimal configuration
module.exports = {
  entry: './src/index.js',
  output: {
    filename: 'bundle.js'
  }
}

// 2. Gradually add features
// Add Loader
// Add Plugin
// Add optimization

2. Log Debugging

Use log output to debug:

javascript
class DebugPlugin {
  apply(compiler) {
    compiler.hooks.compilation.tap('DebugPlugin', (compilation) => {
      console.log('Compilation started');
    });
    
    compiler.hooks.done.tap('DebugPlugin', (stats) => {
      console.log('Build completed');
      console.log('Errors:', stats.compilation.errors.length);
      console.log('Warnings:', stats.compilation.warnings.length);
    });
  }
}

module.exports = {
  plugins: [new DebugPlugin()]
}

3. Conditional Compilation

Use conditional compilation to debug specific modules:

javascript
module.exports = {
  module: {
    rules: [
      {
        test: /\.js$/,
        include: path.resolve(__dirname, 'src/debug'),
        use: 'babel-loader'
      }
    ]
  }
}

Best Practices

1. Monitoring Strategy:

   • Regularly analyze build performance
   • Establish performance benchmarks
   • Continuously optimize

2. Debugging Methods:

   • Use Source Map
   • Enable error overlay
   • Step-by-step debugging

3. Performance Optimization:

   • Analyze bottlenecks
   • Optimize configuration
   • Verify effects

4. Documentation:

   • Record performance data
   • Document optimization process
   • Share best practices

Rspack's performance monitoring and debugging features provide developers with powerful tools. Through reasonable use of these tools, you can continuously optimize build performance and quickly locate and resolve issues.