Re: Delayed response for sleep function

From: Andrey Semashev (andrey.semashev_at_[hidden])
Date: 2022-06-21 11:01:04

On 6/21/22 12:35, Richard Hodges via Boost wrote:
> #include <chrono>
> #include <concepts>
> #include <iostream>
> #include <iomanip>
> #include <ratio>
> #include <unistd.h>
> 
> int
> main()
> {
>     using clock_type = std::chrono::high_resolution_clock;
>     using namespace std::literals;
> 
>     auto t = clock_type::now();
>     auto const t0 = t;
>     auto const t1 = t0 + 1s;
>     while(t < t1)
>     {
>         ::usleep(1);
>         t = clock_type::now();
>     }
> 
>     std::cout
>         << std::chrono::duration_cast<std::chrono::duration<double,
> std::milli>>(t - t0).count()
>         << "ms\n";
> }
> 
> 
> Example output:
> 
> Program returned: 0
> 1000.47ms
> 
> https://godbolt.org/z/bcGPcebP1

Timer precision may depend on the sleep duration. Change to sleep for 10
seconds and you get drift in the order of milliseconds:

10006.5ms

https://godbolt.org/z/Gjxccz5bK