Modifying the system time to the past, sleep_for will cause the program to get stuck.

Question

When the program runs to std::this_thread::sleep_for(std::chrono::milliseconds(1));, if the system time is switched back at this moment, the program will freeze.” I want to know how to avoid this situation.

The following code is for you to test, after you start running it switch the system time to the past and you will see that the program is stuck. Environment: MSVC v143 C++17.

#include <iostream> 
#include <thread> 
using namespace std;  
int main() 
{ 	
	for (int i = 1; i; i++) 	
	{ 		
		cout << i << endl; 		
		std::this_thread::sleep_for(std::chrono::milliseconds(1)); 	
	}  	
	return 0; 
}

I need a viable solution or alternative, please.

Answer 1

Hi, @RL Chen

I reproduced the problem:

Start the program, set the time back 5mins, and then set it to the current time. I still need to wait 5 minutes before the program continues.

For 2 days is set, the program will wait 2 days.

As David said, MSVC seems to use system clock.

You can submit reports on the Developer Community.

Window API is an alternative:

#include<Windows.h>
Such as

Sleep function is not affected by changing the system clock.

Best regards,

Minxin Yu

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