How to close thread detach C++?

Question

I launched thread as detach. How to close thread from main function?

void My()
{
   // actions  
}


void main()
{

    std::thread thr7(receive);
    thr         


        

Answer 1

You can control the thread something like this:

std::atomic_bool running = false; // set to stop thread
std::atomic_bool closed = false; // set by thread to indicate it ended

void detached_thread_function()
{
    running = true;

    // acquire resources

    while(running)
    {
        std::cout << "running" << '\n';
        std::this_thread::sleep_for(std::chrono::seconds(1));
    }

    // release resources

    // set after all resources released
    closed = true;
}

int main()
{
    std::thread(detached_thread_function).detach();

    std::this_thread::sleep_for(std::chrono::seconds(3));

    std::cout << "stopping detached thread" << '\n';

    running = false; // stop thread

    while(!closed) // you could code a timeout here 
        std::this_thread::sleep_for(std::chrono::milliseconds(10));
    // or use a condition variable?

    std::cout << "end program" << '\n';
}

The thread is signaled to end its function and the thread sets a flag to let the main function know it is safe to exit.

If you have multiple threads you can use an atomic counter to exit when it reaches zero.