C++

25.5    Parallel Execution

All algorithms are executed sequentially unless you are programming in C++17 and use an execution policy from the <execution> header as an additional first parameter to an algorithm function template. Not all algorithms support all policies:

• std::execution::seqThe algorithm is not parallelized and runs in the calling thread. However, unlike without this parameter, the steps can be executed in a different order.

• std::execution::parThe steps can be executed in parallel. The work is divided among multiple threads, and each thread executes individual steps sequentially in an unspecified order.

• std::execution::unseq_parThe steps can be executed in parallel and simultaneously. In addition to par, each thread can execute ...