std::thread::hardware_concurrency (3) Linux Manual Page

std::thread::hardware_concurrency – std::thread::hardware_concurrency

Synopsis

static unsigned int hardware_concurrency() noexcept;
(since C++ 11)

Returns the number of concurrent threads supported by the implementation. The value should be considered only a hint.

Parameters

(none)

Return value

Number of concurrent threads supported. If the value is not well defined or not computable, returns 0.

Example

// Run this code

#include <iostream>

#include <thread>
int main()
{
    unsigned int n = std::thread::hardware_concurrency();
    std::cout << n << " concurrent threads are supported.\n";
}

Possible output:

  4 concurrent threads are supported.

See also

hardware_destructive_interference_size min offset to avoid false sharing
hardware_constructive_interference_size max offset to promote true sharing
                                        (constant)
(C++17)