C++ Locking: std::lock_guard or std::scoped_lock? - Which to Choose?

When it comes to C++ locking, developers have two options to choose from: std::lock_guard and std::scoped_lock. Both of these locking mechanisms are used to ensure that a piece of code is executed by only one thread at a time, but there are some differences in their usage and implementation that developers should be aware of.

std::lock_guard

std::lock_guard is a simple and easy-to-use locking mechanism that is available in C++11. It is a class template that can be used to lock a mutex by creating an instance of the class. The mutex is released automatically when the std::lock_guard object goes out of scope, making it a good option for short and simple critical sections.

std::scoped_lock

std::scoped_lock, on the other hand, is a more advanced locking mechanism that was introduced in C++17. It can lock multiple mutexes simultaneously, making it a good option for more complex critical sections. Unlike std::lock_guard, std::scoped_lock requires the developer to explicitly unlock the mutexes that have been locked.

Which to Choose?

Choosing between std::lock_guard and std::scoped_lock depends on the specific use case. If the critical section is short and simple, std::lock_guard is a good option because of its simplicity. However, if the critical section is more complex and involves multiple mutexes, std::scoped_lock is the better choice.

Ultimately, the decision comes down to the specific requirements of the project and the developer's preference. Both std::lock_guard and std::scoped_lock are effective locking mechanisms that can help ensure thread safety in C++ programs.