C++ High Performance

Atomic support in C++

The standard library contains support for atomic variables, sometimes called atomics. An atomic variable is a variable that can safely be used and mutated from multiple threads without introducing data races. An atomic variable may or may not use a lock to protect the data, this depends on the type of the variable and the platform. If the atomic does not use a lock, it is said to be lock-free. You can query the variable in runtime (or compile time since C++17) to be certain that it is lock-free if, for some reason, you need to ensure that it does not use locks internally.

Do you remember the data race example we looked at earlier where two threads updated a global counter? We solved it by adding a mutex lock together ...