Performance Optimization Examples

Here are some Sharp performance optimization examples and best practices.

Memory Optimization

Stream Processing Large Files

import sharp from 'sharp';
import fs from 'fs';

// Stream processing, avoid loading the entire file into memory
fs.createReadStream('large-image.jpg')
  .pipe(sharp().resize(800, 600))
  .pipe(fs.createWriteStream('output.jpg'));

Use Buffer Instead of File

// For small files, using Buffer is more efficient
const inputBuffer = fs.readFileSync('input.jpg');
const outputBuffer = await sharp(inputBuffer)
  .resize(300, 200)
  .jpeg({ quality: 80 })
  .toBuffer();

fs.writeFileSync('output.jpg', outputBuffer);

Release Resources in Time

// Release resources after processing
const image = sharp('input.jpg');
await image.resize(300, 200).toFile('output.jpg');
// image instance will be automatically garbage collected

Concurrency Control

Limit Concurrency

// Set maximum concurrency
sharp.concurrency(4);

// Control concurrency during batch processing
async function batchProcess(files) {
  const batchSize = 4;
  const results = [];
  
  for (let i = 0; i < files.length; i += batchSize) {
    const batch = files.slice(i, i + batchSize);
    const batchPromises = batch.map(file => 
      sharp(file).resize(300, 200).jpeg().toFile(`output_${file}`)
    );
    
    await Promise.all(batchPromises);
    results.push(...batch);
  }
  
  return results;
}

Use Queue Processing

class ImageProcessor {
  constructor(concurrency = 4) {
    this.concurrency = concurrency;
    this.queue = [];
    this.running = 0;
  }
  
  async add(task) {
    return new Promise((resolve, reject) => {
      this.queue.push({ task, resolve, reject });
      this.process();
    });
  }
  
  async process() {
    if (this.running >= this.concurrency || this.queue.length === 0) {
      return;
    }
    
    this.running++;
    const { task, resolve, reject } = this.queue.shift();
    
    try {
      const result = await task();
      resolve(result);
    } catch (error) {
      reject(error);
    } finally {
      this.running--;
      this.process();
    }
  }
}

// Usage example
const processor = new ImageProcessor(4);

for (const file of files) {
  processor.add(async () => {
    await sharp(file).resize(300, 200).jpeg().toFile(`output_${file}`);
  });
}

Cache Optimization

Cache Processing Results

const cache = new Map();

async function processWithCache(inputPath, width, height) {
  const key = `${inputPath}_${width}_${height}`;
  
  if (cache.has(key)) {
    return cache.get(key);
  }
  
  const result = await sharp(inputPath)
    .resize(width, height)
    .jpeg({ quality: 80 })
    .toBuffer();
  
  cache.set(key, result);
  return result;
}

Clear Sharp Cache

// Clear cache periodically to release memory
setInterval(() => {
  sharp.cache(false);
}, 60000); // Clear cache every minute

Algorithm Selection

Select Appropriate Resize Algorithm

// Use faster algorithm for shrinking
await sharp('input.jpg')
  .resize(300, 200, { kernel: sharp.kernel.cubic })
  .toFile('output.jpg');

// Use higher quality algorithm for enlarging
await sharp('input.jpg')
  .resize(1200, 800, { kernel: sharp.kernel.lanczos3 })
  .toFile('output.jpg');

Batch Processing Optimization

async function optimizedBatchProcess(files) {
  // Group by size
  const smallFiles = [];
  const largeFiles = [];
  
  for (const file of files) {
    const metadata = await sharp(file).metadata();
    if (metadata.width * metadata.height < 1000000) {
      smallFiles.push(file);
    } else {
      largeFiles.push(file);
    }
  }
  
  // Use fast algorithm for small files
  await Promise.all(smallFiles.map(file =>
    sharp(file)
      .resize(300, 200, { kernel: sharp.kernel.cubic })
      .jpeg({ quality: 80 })
      .toFile(`output_${file}`)
  ));
  
  // Use higher quality algorithm for large files
  await Promise.all(largeFiles.map(file =>
    sharp(file)
      .resize(800, 600, { kernel: sharp.kernel.lanczos3 })
      .jpeg({ quality: 90 })
      .toFile(`output_${file}`)
  ));
}

Network Optimization

Streaming Response

// Express.js example
app.get('/image/:filename', async (req, res) => {
  const filename = req.params.filename;
  
  try {
    const imageStream = sharp(`images/${filename}`)
      .resize(300, 200)
      .jpeg({ quality: 80 });
    
    res.set('Content-Type', 'image/jpeg');
    imageStream.pipe(res);
  } catch (error) {
    res.status(404).send('Image not found');
  }
});

Conditional Processing

app.get('/image/:filename', async (req, res) => {
  const { filename } = req.params;
  const { width, height, quality = 80 } = req.query;
  
  try {
    let image = sharp(`images/${filename}`);
    
    if (width || height) {
      image = image.resize(parseInt(width), parseInt(height));
    }
    
    if (req.headers.accept?.includes('image/webp')) {
      image = image.webp({ quality: parseInt(quality) });
      res.set('Content-Type', 'image/webp');
    } else {
      image = image.jpeg({ quality: parseInt(quality) });
      res.set('Content-Type', 'image/jpeg');
    }
    
    image.pipe(res);
  } catch (error) {
    res.status(404).send('Image not found');
  }
});

Monitoring and Debugging

Performance Monitoring

async function processWithTiming(inputPath, outputPath) {
  const startTime = Date.now();
  
  try {
    await sharp(inputPath)
      .resize(800, 600)
      .jpeg({ quality: 80 })
      .toFile(outputPath);
    
    const endTime = Date.now();
    console.log(`Processing time: ${endTime - startTime}ms`);
  } catch (error) {
    console.error('Processing failed:', error.message);
  }
}

Memory Usage Monitoring

const process = require('process');

function logMemoryUsage() {
  const usage = process.memoryUsage();
  console.log('Memory usage:', {
    rss: `${Math.round(usage.rss / 1024 / 1024)} MB`,
    heapTotal: `${Math.round(usage.heapTotal / 1024 / 1024)} MB`,
    heapUsed: `${Math.round(usage.heapUsed / 1024 / 1024)} MB`,
    external: `${Math.round(usage.external / 1024 / 1024)} MB`
  });
}

// Record memory usage before and after processing
logMemoryUsage();
await sharp('input.jpg').resize(800, 600).toFile('output.jpg');
logMemoryUsage();

Error Handling and Retry

Retry Mechanism

async function processWithRetry(inputPath, outputPath, maxRetries = 3) {
  for (let attempt = 1; attempt <= maxRetries; attempt++) {
    try {
      await sharp(inputPath)
        .resize(800, 600)
        .jpeg({ quality: 80 })
        .toFile(outputPath);
      
      console.log(`Processing successful, attempt: ${attempt}`);
      return;
    } catch (error) {
      console.error(`Attempt ${attempt} failed:`, error.message);
      
      if (attempt === maxRetries) {
        throw new Error(`Processing failed, retried ${maxRetries} times`);
      }
      
      // Wait for a while before retrying
      await new Promise(resolve => setTimeout(resolve, 1000 * attempt));
    }
  }
}

Error Classification Processing

async function robustProcess(inputPath, outputPath) {
  try {
    await sharp(inputPath)
      .resize(800, 600)
      .jpeg({ quality: 80 })
      .toFile(outputPath);
  } catch (error) {
    if (error.code === 'VipsForeignLoad') {
      console.error('Unsupported image format');
    } else if (error.code === 'VipsForeignLoadLimit') {
      console.error('Image too large, trying to shrink');
      // Try to process a smaller version
      await sharp(inputPath, { limitInputPixels: 268402689 })
        .resize(400, 300)
        .jpeg({ quality: 80 })
        .toFile(outputPath);
    } else if (error.code === 'ENOSPC') {
      console.error('Disk space不足');
    } else {
      console.error('Unknown error:', error.message);
    }
  }
}

Best Practices Summary

1. Select Appropriate Processing Method

// Small file: direct processing
if (fileSize < 1024 * 1024) {
  await sharp(file).resize(300, 200).toFile(output);
}

// Large file: streaming processing
else {
  fs.createReadStream(file)
    .pipe(sharp().resize(300, 200))
    .pipe(fs.createWriteStream(output));
}

2. Batch Processing Optimization

// Use Promise.all for concurrent processing
const promises = files.map(file => 
  sharp(file).resize(300, 200).jpeg().toFile(`output_${file}`)
);
await Promise.all(promises);

3. Memory Management

// Clear cache periodically
setInterval(() => {
  sharp.cache(false);
}, 300000); // Clear cache every 5 minutes

4. Error Handling

// Always use try-catch
try {
  await sharp(input).resize(300, 200).toFile(output);
} catch (error) {
  console.error('Processing failed:', error.message);
  // Provide a backup plan
}

Related Links

• Basic Examples
• Advanced Examples
• API Reference
• Installation Guide