Concurrency in C# (.NET): Asynchrony, Parallelism, and Multithreading

Modern applications rarely run in single-threaded mode. Responsiveness, scalability, and efficient resource utilization directly depend on the developer's ability to properly structure concurrent processes. The book "Concurrency in C# (.NET)" is a comprehensive guide that will help you master all aspects of parallel and asynchronous programming in the .NET ecosystem.

The author systematically covers the topic: from basic concepts (threads, tasks, synchronization) to advanced techniques (channels, dataflow, reactive extensions). You will learn to avoid common mistakes — deadlocks, race conditions, and thread pool overload.

What you will learn from the book:

• Concurrency Basics — how multithreading, asynchrony, and parallelism differ, and when to use which.
• Task and async/await — deep dive into the TAP (Task-based Asynchronous Pattern), working with CancellationToken and ValueTask.
• Threads and Thread Pool — managing ThreadPool, creating background and foreground threads, thread-local data.
• Synchronization — lock, Monitor, SemaphoreSlim, ReaderWriterLock, barriers, and spin locks.
• Parallel Collections — ConcurrentDictionary, ConcurrentQueue, BlockingCollection, Channel for producer-consumer.
• Parallel LINQ and TPL — parallelizing queries, Parallel.For/ForEach, managing the degree of parallelism.
• Reactive Programming — System.Reactive (Rx.NET), processing event and data streams.
• Debugging and Profiling — Visual Studio tools, diagnosing races, leaks, and deadlocks.
• Advanced Scenarios — Dataflow (ActionBlock, TransformBlock), IAsyncEnumerable, asynchronous streams in C# 8+.

Who this book is for:

• C# developers who want to write fast and responsive applications.
• Backend engineers working with ASP.NET Core and high-load services.
• Professionals transitioning from synchronous to asynchronous code and wanting to avoid pitfalls.
• Those preparing for interviews for Senior .NET Developer positions.

The book contains many real-world examples ready for use in projects. Each chapter ends with practical exercises and self-test questions. You will not just read theory — you will learn to design concurrent systems that work stably and efficiently.

"Concurrency in C# (.NET)" is an essential book for every .NET developer striving for professional growth. Whether you are writing a desktop application, a web service, or a cloud function, the knowledge from this book will help you make your code faster, safer, and clearer.