Ottimizza le prestazioni

Ottimizzazione di un'API Node.js Express per 1.000 RPS

Per gestire 1.000 richieste al secondo (RPS) in un'API Node.js Express, devi concentrarti su diverse aree chiave di ottimizzazione. Ecco un approccio completo:

1. Indicizzazione del database

Una corretta indicizzazione del database è fondamentale per le API ad alte prestazioni.

Esempio MongoDB:

1// Create indexes for frequently queried fields
2const mongoose = require('mongoose');
3const userSchema = new mongoose.Schema({
4  email: String,
5  username: String,
6  createdAt: Date
7});
8
9// Create single field indexes
10userSchema.index({ email: 1 });
11userSchema.index({ username: 1 });
12
13// Create compound index for queries that filter on multiple fields
14userSchema.index({ createdAt: -1, username: 1 });
15
16// Create text index for search functionality
17userSchema.index({ username: 'text', email: 'text' });
18
19const User = mongoose.model('User', userSchema);

Esempio SQL (utilizzando Sequelize):

1const User = sequelize.define('User', {
2  email: DataTypes.STRING,
3  username: DataTypes.STRING,
4  createdAt: DataTypes.DATE
5});
6
7// After defining models, create indexes
8(async () => {
9  await sequelize.sync();
10  // Create indexes
11  await sequelize.query('CREATE INDEX idx_users_email ON Users(email)');
12  await sequelize.query('CREATE INDEX idx_users_username ON Users(username)');
13  await sequelize.query('CREATE INDEX idx_users_created_at ON Users(createdAt)');
14})();

2. Implementazione del caching

Memorizzazione nella cache Redis:

1const express = require('express');
2const redis = require('redis');
3const { promisify } = require('util');
4const app = express();
5
6// Create Redis client
7const redisClient = redis.createClient({
8  host: process.env.REDIS_HOST || 'localhost',
9  port: process.env.REDIS_PORT || 6379
10});
11
12// Promisify Redis get and set methods
13const getAsync = promisify(redisClient.get).bind(redisClient);
14const setAsync = promisify(redisClient.set).bind(redisClient);
15
16// Middleware for caching
17const cacheMiddleware = (duration) => async (req, res, next) => {
18  const key = `api:${req.originalUrl}`;
19  
20  try {
21    const cachedData = await getAsync(key);
22    
23    if (cachedData) {
24      return res.json(JSON.parse(cachedData));
25    }
26    
27    // Store original send function
28    const originalSend = res.send;
29    
30    // Override send
31    res.send = function(body) {
32      setAsync(key, body, 'EX', duration);
33      return originalSend.call(this, body);
34    };
35    
36    next();
37  } catch (err) {
38    console.error('Cache error:', err);
39    next();
40  }
41};
42
43// Apply cache middleware to routes
44app.get('/api/users', cacheMiddleware(60), async (req, res) => {
45  // Database query here
46  const users = await User.find();
47  res.json(users);
48});

Caching in memoria con Node-Cache:

1const NodeCache = require('node-cache');
2const cache = new NodeCache({ stdTTL: 60 }); // Default TTL: 60 seconds
3
4// Cache middleware
5function cacheMiddleware(key, ttl) {
6  return (req, res, next) => {
7    const cacheKey = key || req.originalUrl;
8    const cachedResponse = cache.get(cacheKey);
9    
10    if (cachedResponse) {
11      return res.json(cachedResponse);
12    }
13    
14    const originalJson = res.json;
15    res.json = function(data) {
16      cache.set(cacheKey, data, ttl || 60);
17      originalJson.call(this, data);
18    };
19    
20    next();
21  };
22}
23
24// Usage
25app.get('/api/products', cacheMiddleware('products', 300), async (req, res) => {
26  const products = await Product.find();
27  res.json(products);
28});

3. Elaborazione asincrona

Utilizzo di Bull Queue per i lavori in background:

1const Queue = require('bull');
2const express = require('express');
3const app = express();
4
5// Create processing queue
6const emailQueue = new Queue('email-sending', {
7  redis: {
8    host: process.env.REDIS_HOST || 'localhost',
9    port: process.env.REDIS_PORT || 6379
10  }
11});
12
13// API endpoint that offloads work to the queue
14app.post('/api/users', async (req, res) => {
15  try {
16    // Save user to database
17    const user = await User.create(req.body);
18    
19    // Add welcome email job to queue instead of sending it synchronously
20    await emailQueue.add({
21      to: user.email,
22      subject: 'Welcome!',
23      template: 'welcome',
24      userId: user.id
25    }, {
26      attempts: 3,
27      backoff: {
28        type: 'exponential',
29        delay: 1000
30      }
31    });
32    
33    // Respond immediately without waiting for email
34    res.status(201).json(user);
35  } catch (err) {
36    res.status(500).json({ error: err.message });
37  }
38});
39
40// Process queue in a separate process
41emailQueue.process(async (job) => {
42  const { to, subject, template, userId } = job.data;
43  // Send email logic here
44  await sendEmail(to, subject, template, { userId });
45  return { sent: true };
46});
47
48// Handle queue events
49emailQueue.on('completed', job => {
50  console.log(`Job ${job.id} completed`);
51});
52
53emailQueue.on('failed', (job, err) => {
54  console.error(`Job ${job.id} failed with error: ${err.message}`);
55});

4. Ottimizzazione del server

Modalità cluster:

1const cluster = require('cluster');
2const os = require('os');
3const express = require('express');
4
5if (cluster.isMaster) {
6  // Get the number of available CPU cores
7  const numCPUs = os.cpus().length;
8  
9  console.log(`Master process running. Forking ${numCPUs} workers`);
10  
11  // Fork workers for each available CPU
12  for (let i = 0; i < numCPUs; i++) {
13    cluster.fork();
14  }
15  
16  // Handle worker crashes
17  cluster.on('exit', (worker, code, signal) => {
18    console.log(`Worker ${worker.process.pid} died. Restarting...`);
19    cluster.fork();
20  });
21} else {
22  // Worker processes share the same port
23  const app = express();
24  
25  // Your Express routes and middleware here
26  app.get('/', (req, res) => {
27    res.send('Hello from worker ' + process.pid);
28  });
29  
30  const PORT = process.env.PORT || 3000;
31  app.listen(PORT, () => {
32    console.log(`Worker ${process.pid} started and listening on port ${PORT}`);
33  });
34}

Utilizzo di PM2:

1// app.js - Your Express application
2const express = require('express');
3const app = express();
4
5// Routes and middleware here
6
7const PORT = process.env.PORT || 3000;
8app.listen(PORT, () => {
9  console.log(`Server running on port ${PORT}`);
10});
11
12// ecosystem.config.js - PM2 configuration
13module.exports = {
14  apps: [{
15    name: "api-server",
16    script: "./app.js",
17    instances: "max", // Use all available CPUs
18    exec_mode: "cluster",
19    watch: false,
20    max_memory_restart: "1G",
21    env: {
22      NODE_ENV: "production",
23      PORT: 3000
24    }
25  }]
26};
27
28// Run with: pm2 start ecosystem.config.js

5. Compressione della risposta

1const express = require('express');
2const compression = require('compression');
3const app = express();
4
5// Add compression middleware
6app.use(compression({
7  level: 6, // Default compression level
8  threshold: 1024, // Only compress responses larger than 1KB
9  filter: (req, res) => {
10    // Don't compress responses with this header
11    if (req.headers['x-no-compression']) {
12      return false;
13    }
14    // Use compression filter function from the module
15    return compression.filter(req, res);
16  }
17}));
18
19// Your routes here

6. Connessioni in pool

1// For MongoDB with Mongoose
2mongoose.connect('mongodb://localhost/myapp', {
3  poolSize: 10, // Maintain up to 10 socket connections
4  serverSelectionTimeoutMS: 5000,
5  socketTimeoutMS: 45000
6});
7
8// For PostgreSQL with pg
9const { Pool } = require('pg');
10const pool = new Pool({
11  host: 'localhost',
12  database: 'myapp',
13  user: 'postgres',
14  password: 'password',
15  max: 20, // Maximum number of clients in the pool
16  idleTimeoutMillis: 30000,
17  connectionTimeoutMillis: 2000
18});
19
20// Use the pool in your routes
21app.get('/api/data', async (req, res) => {
22  const client = await pool.connect();
23  try {
24    const result = await client.query('SELECT * FROM items');
25    res.json(result.rows);
26  } finally {
27    client.release(); // Return client to pool
28  }
29});

7. Limitazione della velocità

1const rateLimit = require('express-rate-limit');
2
3// Create rate limiter
4const apiLimiter = rateLimit({
5  windowMs: 15 * 60 * 1000, // 15 minutes
6  max: 100, // Limit each IP to 100 requests per windowMs
7  standardHeaders: true, // Return rate limit info in the `RateLimit-*` headers
8  legacyHeaders: false, // Disable the `X-RateLimit-*` headers
9  message: 'Too many requests from this IP, please try again after 15 minutes'
10});
11
12// Apply rate limiting to all API routes
13app.use('/api/', apiLimiter);
14
15// Different limits for specific endpoints
16const createAccountLimiter = rateLimit({
17  windowMs: 60 * 60 * 1000, // 1 hour
18  max: 5, // 5 accounts per hour per IP
19  message: 'Too many accounts created from this IP, please try again after an hour'
20});
21
22app.post('/api/create-account', createAccountLimiter, (req, res) => {
23  // Create account logic
24});

8. Monitoraggio e ottimizzazione delle prestazioni

1const express = require('express');
2const responseTime = require('response-time');
3const app = express();
4
5// Add response time header
6app.use(responseTime());
7
8// Basic request logging
9app.use((req, res, next) => {
10  const start = Date.now();
11  
12  res.on('finish', () => {
13    const duration = Date.now() - start;
14    console.log(`${req.method} ${req.originalUrl} ${res.statusCode} ${duration}ms`);
15  });
16  
17  next();
18});
19
20// For more advanced monitoring, consider using:
21// - Prometheus + Grafana
22// - New Relic
23// - Datadog

Implementando queste ottimizzazioni, l'API Node.js Express dovrebbe essere ben attrezzata per gestire 1.000 RPS. Ricordati di:

1. Profila la tua candidatura per identificare i colli di bottiglia
2. Implementa strategicamente il caching per i dati a cui si accede di frequente
3. Usa gli indici del database per i modelli di interrogazione più comuni
4. Affida le attività che richiedono un uso intensivo della CPU ai lavoratori in background
5. Scalabilità orizzontale utilizzando il clustering o l'orchestrazione dei contenitori
6. Monitora le prestazioni in produzione per ottimizzare continuamente