Execution Policies (Incomplete Draft)¶

Execution Policies ¶

std::execution::seq: sequential execution as if not specified at all
std::execution::par: in parallel, multiple threads. Might fall back to std::execution::seq though.
std::execution::par_unseq: use vectorization. Might fall back to std::execution::seq though.

And Exceptions?¶

Parallel execution (std::execution::par and std::execution::par_unseq) does not like exceptions
Process is terminated by default (std::abort())
⟶ You data should not throw on access

Examples ¶

code/parallel-sort.cpp¶

#include <random>
#include <algorithm>
#include <execution>
#include <iostream>

int main()
{
    std::random_device rd;
    std::vector<int> numbers;
    for (int _=0; _<100000; _++)
        numbers.push_back(rd());

    std::sort(std::execution::par, numbers.begin(), numbers.end());
    for (int elem: numbers)
        std::cout << elem << std::endl;
    return 0;
}

code/parallel-foreach.cpp¶

#include <random>
#include <algorithm>
#include <execution>
#include <iostream>

int main()
{
    std::vector<int> numbers;
    for (int i=0; i<1000; i++)
        numbers.push_back(i);

    std::for_each(
        std::execution::par_unseq, 
        numbers.begin(), numbers.end(), 
        [](int elem){ std::cout << elem << std::endl; });

    return 0;
}