提升thread_group线程限制器

我试图随时限制线程数，使其等于可用内核的最大数量。以下方法是否合理？有没有更好的选择？ 谢谢！

    boost::thread_group threads;
    iThreads = 0;
    for (int i = 0; i <  Utility::nIterations; i++)
    {
        threads.create_thread(
            boost::bind(&ScenarioInventory::BuildInventoryWorker, this,i));
        thread_limiter.lock();
        iThreads++;
        thread_limiter.unlock();
        while (iThreads > nCores)
            std::this_thread::sleep_for(std::chrono::milliseconds(1)); 
    }
threads.join_all();

void ScenarioInventory::BuildInventoryWorker(int i)
{
    //code code code....
    thread_limiter.lock();
    iThreads--;
    thread_limiter.unlock();
}