C++ Threading and Concurrency

This article serves as an advanced crash course on C++ multithreading and concurrency. It covers the fundamental building blocks provided by the C++ Standard Library to manage threads and safe data access. The guide progresses from basic thread creation to synchronization primitives and finally to higher-level concurrency models.

The material explains the difference between concurrency (multiple tasks making progress) and parallelism (multiple tasks running simultaneously). It details how to use std::thread to manage execution currents and highlights the importance of managing shared data to avoid race conditions. The article also provides safe coding practices, such as using lock guards over raw mutexes and leveraging atomic types for lock-free synchronization where appropriate.

Key Concepts

• std::thread: The standard class used to create and manage individual execution threads. It supports creating threads via function pointers, lambda functions, or functors.
• Race Conditions: A critical issue that occurs when distinct threads simultaneously access shared data and at least one thread modifies it, leading to undefined behavior.
• Atomics: Specialized types (std::atomic) that provide thread-safe operations without the overhead of explicit locking, ensuring no race conditions for specific variables.
• Mutexes and Lock Guards: std::mutex is used to protect shared resources. The article recommends using RAII wrappers like std::lock_guard or std::scoped_lock to automatically manage lock lifecycles and prevent deadlocks.
• Condition Variables: Synchronization primitives that allow threads to block and wait for a specific condition to become true, often used for event handling between threads.
• Tasks (std::async): A higher-level abstraction than threads, preferred for returning values from asynchronous operations. It uses std::future and std::promise to manage results.