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

For a long time, PHP was perceived as a strictly synchronous language where each request is processed in a single thread. However, the modern PHP ecosystem offers powerful tools for concurrent and parallel code execution. The book "Concurrency in PHP" is a practical guide that breaks down myths and shows how to write fast, responsive, and scalable PHP applications.

The book is intended for middle and senior developers who are already proficient in PHP and want to go beyond the traditional synchronous model. You will learn how to use coroutines (Fibers, Amphp, ReactPHP), multithreading (pthreads, parallel), inter-process communication, and asynchronous handlers for queues and events.

• Chapters 1–3. Fundamental concepts: race conditions, locks, deadlocks, memory models. Comparison of threads, processes, and coroutines.
• Chapters 4–6. Working with parallel and pthreads: creating threads, shared memory, synchronization via mutexes and semaphores.
• Chapters 7–9. Asynchronous programming: event loop, Promises, coroutines on Fibers, Amphp and ReactPHP libraries.
• Chapters 10–12. Practical cases: high-load API, WebSocket server, parser for a million URLs, background video processing.
• Chapters 13–14. Integration with queues (RabbitMQ, Redis), monitoring and profiling concurrent applications.

The reader will learn:

• How to correctly choose a concurrency model for a specific task;
• How to avoid typical mistakes (deadlock, race condition, memory leaks);
• How to build fault-tolerant systems with asynchronous processing;
• How to use modern PHP libraries and extensions for parallelism;
• How to optimize performance by 5–10 times on suitable tasks.

The book contains numerous code examples ready to run in real projects. All examples were tested on PHP 8.2+ and are compatible with modern frameworks (Laravel, Symfony). After reading, you will be able to confidently design high-load systems in PHP using the full arsenal of concurrent tools.

Who this book is for: PHP developers, DevOps engineers, architects, and anyone who wants to understand how to make PHP work faster and more efficiently.