为什么我的 test_time 没有接近 5 秒？

Question

I'am trying to make a time meter. My OS is Windows.
Here is a small piece of code that gives a strange result.
If a thread sleeps for 1ms and does this 5000 times, then I would expect it to take roughly 5 seconds.
But I get as a result that test_time = 12.8095
Do not understand why?
How can I fix the code so that I get a time meter that can measure durations of about 1 millisecond?

std::atomic_bool work = true;
    size_t cnt{};
    std::chrono::duration<double> operation_time;
    double test_time;
            auto start_time_ = std::chrono::high_resolution_clock::now();
            std::thread counter_ = std::thread([&work, &cnt]() {
                while (work) {
                    std::this_thread::sleep_for(std::chrono::milliseconds(1));
                    cnt++;
                    if (cnt >= 5000)
                        work = false;
                }
                });
            
            if (counter_.joinable())
                counter_.join();
            operation_time = std::chrono::duration<double>(std::chrono::high_resolution_clock::now() - start_time_);
            test_time = operation_time.count();

            std::cout << "test_time = " << test_time << std::endl;

Answer 1

As previously stated, sleep_for

Blocks the execution of the current thread for at least the specified sleep_duration.

The answer to your question would be to use sleep_until

Blocks the execution of the current thread until specified sleep_time has been reached.

That means, take the current timestamp, add 1 ms and sleep until that time.

See:

• https://en.cppreference.com/w/cpp/thread/sleep_for
• https://en.cppreference.com/w/cpp/thread/sleep_until