Concurrency in PHP: Asynchrony, Parallelism, and Multithreading in Practice

PHP has long been considered a purely synchronous language, but the modern realities of web development require the ability to work with concurrent tasks. The book "Concurrency in PHP" is a comprehensive guide that dispels the myth that PHP is incapable of asynchrony and parallelism. The author, Alexey Voronov, a senior developer with 10 years of experience, systematically guides the reader from the basics of synchronous programming to complex architectures based on coroutines and event loops.

Who is this book for?

• Junior+ and Middle PHP developers who want to improve the performance of their applications.
• System architects designing high-load services (chat bots, API gateways, parsers).
• Developers transitioning from other languages (Node.js, Python, Go) who want to apply their knowledge of concurrency in the PHP ecosystem.
• Those who want to understand the internal workings of popular libraries: ReactPHP, Amp, Swoole.

What will you learn from the book?

• Theory basics: the difference between parallelism and concurrency, blocking and non-blocking operations, the I/O model.
• Multithreading: working with the pthreads and parallel extensions: creating thread pools, synchronization, mutexes.
• Asynchronous programming: event loop, promises, reactive extensions (RxPHP), generators as lightweight coroutines.
• Fiber (PHP 8.1+): a new era of concurrency — how Fiber works, priorities, data transfer between fibers.
• Practical use cases: parallel processing of thousands of HTTP requests, building a WebSocket server, asynchronous task queues, working with microservices.
• Benchmarking and profiling: how to measure performance, avoid deadlocks and race conditions.

Why should you read it?

The book is not overloaded with theory — each section ends with a practical task and ready-made code. You will learn to write efficient long-running processes (daemons), real-time event handlers, and scalable applications without excessive memory usage. A separate chapter is dedicated to comparing popular libraries and frameworks (ReactPHP vs Amp vs Swoole) with migration examples.

This is not just a reference book, but a desk book for those who want to take their PHP projects to a new level of performance. Whether you are building an API for a million users or writing a data parser — concurrency will become your main tool.