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std::thread::hardware_concurrency

From cppreference.com
< cpp‎ | thread‎ | thread
 
 
Concurrency support library
Threads
(C++11)
(C++20)
this_thread namespace
(C++11)
(C++11)
(C++11)
Cooperative cancellation
Mutual exclusion
(C++11)
Generic lock management
(C++11)
(C++11)
(C++11)
(C++11)
(C++11)
Condition variables
(C++11)
Semaphores
Latches and Barriers
(C++20)
(C++20)
Futures
(C++11)
(C++11)
(C++11)
(C++11)
Safe Reclamation
(C++26)
Hazard Pointers
Atomic types
(C++11)
(C++20)
Initialization of atomic types
(C++11)(deprecated in C++20)
(C++11)(deprecated in C++20)
Memory ordering
Free functions for atomic operations
Free functions for atomic flags
 
 
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.

Contents

[edit] Parameters

(none)

[edit] Return value

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

[edit] Example

#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.

[edit] See also

min offset to avoid false sharing
max offset to promote true sharing
(constant) [edit]