<execution>

Describes the execution policies for parallel algorithms.

Syntax

namespace std {
    template<class T> inline constexpr bool is_execution_policy_v = is_execution_policy<T>::value;
}
namespace std::execution {
    inline constexpr sequenced_policy seq { unspecified };
    inline constexpr parallel_policy par { unspecified };
    inline constexpr parallel_unsequenced_policy par_unseq { unspecified };
}

Classes and Structs

Name	Description
is_execution_policy Struct	Detects execution policies to exclude certain function signatures from otherwise ambiguous overload resolution participation.
parallel_policy Class	Used as a unique type to disambiguate parallel algorithm overloading. Indicates that a parallel algorithm’s execution may be parallelized.
parallel_unsequenced_policy Class	Used as a unique type to disambiguate parallel algorithm overloading. Indicates that a parallel algorithm’s execution may be parallelized and vectorized.
sequenced_policy Class	Used as a unique type to disambiguate parallel algorithm overloading. Specifies that a parallel algorithm’s execution may not be parallelized.

Microsoft Specific

When parallel_policy or parallel_unsequenced_policy cause the algorithm to be parallelized, the parallel execution uses Windows Thread Pool; see Thread Pools. The number of concurrent threads is limited to the thread pool default (currently 500). The number of threads concurrently executing on hardware is currently limited by the number of logical processors in the current process's processor group, so it is effectively limited to 64; see Processor Groups. The maximum number of chunks for data partitioning is also currently based on the number of logical processors in the current process's processor group.

Requirements

Header: <execution>

Namespace: std

See also

Header files reference
Thread safety in the C++ standard library
C++ standard library reference