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Summary - Performance

Combine perf_hooks, memoryUsage and profiling to write a benchmark tool.

Summary - Performance

In this group you learned performance tools: time measurement with perf_hooks, memory monitoring with process.memoryUsage(), CPU profiling with inspector. Event loop latency is an early warning for bottlenecks.

The optimization order: measure, find the bottleneck, remove it, measure again. Move CPU work to a worker thread, make I/O asynchronous, cache repeated calculations. Avoid premature optimization; always rely on data.

Performance checklist

Performance checklist: (1) Event loop latency should be under 10 ms. (2) heapUsed should grow steadily, without leaks. (3) CPU profiles should show the bottleneck function. (4) Response times should be consistent.

In production, APM tools (New Relic, Datadog) collect these metrics automatically. Adding your own measurements is a good habit; but use existing tools first.

Practice Check if now is a function

Import performance from perf_hooks. Log typeof performance.now === "function".

Starter code

index.js
// import the module, get the timer

// log if now is a function

Sample solution

index.js
const { performance } = require("perf_hooks");
console.log(typeof performance.now === "function");

Expected output

true

Questions and answers

Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.

1 What is the first step before optimization?

  • Kodu yeniden yazmak
  • Measuring (profiling) Correct answer
  • Installing a new module
  • Switching servers

Explanation: Measure first, then improve.

2 Match each piece to its role

Term Meaning
perf_hooks Measures time
process.memoryUsage() Gives memory
inspector CPU profile
event loop latency Measures delay

All lessons in Advanced

1 Clustering

  1. cluster module
  2. cluster.fork
  3. Worker IPC
  4. cluster.isMaster
  5. Graceful reload
  6. Summary - Clustering

2 Worker threads

  1. worker_threads
  2. Worker
  3. postMessage
  4. MessageChannel
  5. SharedArrayBuffer
  6. Summary - Worker threads

3 Performance

  1. perf_hooks
  2. Event loop latency
  3. Memory usage
  4. CPU profiling
  5. Optimization
  6. Summary - Performance

4 Security

  1. Helmet
  2. CORS
  3. Rate limiting
  4. Input validation
  5. JWT
  6. Summary - Security

5 MongoDB

  1. Mongoose
  2. Schema
  3. Model
  4. Query
  5. Aggregate
  6. Summary - MongoDB

6 SQL database

  1. pg module
  2. Pool
  3. Parameterized query
  4. Transactions
  5. Sequelize
  6. Summary - SQL database

7 WebSocket

  1. ws module
  2. WebSocket server
  3. Connection
  4. Message
  5. Broadcast
  6. Summary - WebSocket

8 Realtime

  1. Socket.io
  2. io.on
  3. emit and on
  4. Rooms
  5. Namespaces
  6. Summary - Realtime

9 Microservice basics

  1. What are microservices?
  2. Service communication
  3. API gateway
  4. Service discovery
  5. Circuit breaker
  6. Summary - Microservices

10 Message queue

  1. What are message queues?
  2. Bull
  3. Producer
  4. Consumer
  5. Retry and backoff
  6. Summary - Message queue

11 Logging

  1. Winston
  2. Log levels
  3. Transports
  4. Structured logging
  5. Pino
  6. Summary - Logging

12 Configuration

  1. dotenv
  2. Environment variables
  3. Config hierarchy
  4. Validation
  5. Secrets management
  6. Summary - Configuration

13 Advanced testing

  1. Integration tests
  2. Supertest
  3. Test database
  4. Coverage
  5. E2E tests
  6. Summary - Advanced testing

14 Advanced final

  1. Project design
  2. Express + DB
  3. WebSocket
  4. Security
  5. Putting it together