Thread: Sleep stops working after 15 minutes without wifi

You haven't provided the entire program. You don't need to open and close the file each time you run the loop. tdif is a long int, NOT a float.

Try my version, which works on Linux with gcc, and compare the code with yours:

Code:

#include <stdio.h>
#include <time.h>
#include <unistd.h>

int main(void)
{
   FILE *log = NULL;
   time_t start = 0;
   time_t stop = 0;
   time_t tdif = 0;

   time(&start);
   log=fopen("./log.txt","a");

   do{
      time(&stop);
      tdif=difftime(stop, start);
      fprintf(log," %ld\n", tdif);
      sleep(1);
   }
   while(tdif<32);
   
   fclose(log);

   return 0;
}

Originally Posted by CodeMonkey

When you say that the program stops, what do you mean exactly?

I'm imagining that your program is receiving a signal from the operating system. That's likely to happen anywhere you sleep, since most of the program's wall time is likely spent in the sleep.

Does your program print anything before stopping? Do you know the process's exit status?

I can't tell you exactly what happens because all I have is a log with fprintf's in it. All I can see is that last thing in the log is fprintf from do-while loop at some random seconds.

And by stopping I mean, the program doesn't go to next iteration of the loop. It doesn't break out of do-while loop, because if it did that it would print out a line to a log. It just disappears from htop, like it crashed.

I'm not sure how to check process's exit status.

This is raspberry pi, as far as I know, it doesn't have a real time clock. Could that be an issue when it doesn't have wifi to check the time?

Originally Posted by john.c

You are saying that if you start the program it will run for 15 minutes and then "stop". I'm not familiar with the rasberry pi. Is it possible the program is segfaulting? Can you tell? If it is segfaulting then the problem is probably elsewhere and just happens to show up where you found it. Is it always exactly the same amount of time? What happens if you replace the chunk of code that you've shown with sleep(32)?

Yep, that's what I'm saying. sleep(32) does the same thing. What I did here is second or third attempt to make things work.
It's not always the same amount of time. It's roughly 15 minutes, but sometimes it will crash at 6th second, sometimes at 31st second, sometimes at 14th second etc... I could measure it by a stopwatch though.

I don't know how to tell if it's segfaulting. I just enable the wifi after 20 minutes and see what happened.

rstanley, my code also works, when the wifi is on . I put your code on my raspberry pi to see what happens, let you know in 15 minutes. And I know I don't need to open and close the file that often, but I did that in case when the program crashes in the middle of the loop, I would at least see it entered the loop and spent some amount of seconds in it.

Originally Posted by GhostLoveScore

rstanley, my code also works, when the wifi is on . I put your code on my raspberry pi to see what happens, let you know in 15 minutes. And I know I don't need to open and close the file that often, but I did that in case when the program crashes in the middle of the loop, I would at least see it entered the loop and spent some amount of seconds in it.

Post a full program that fails, using your code, and let us know what compiler you are using.

Originally Posted by rstanley

Post a full program that fails, using your code, and let us know what compiler you are using.

This is your code, but I added endless while loop and print to file. It also stops working after about 15 minutes. gcc compiler.

Code:

#include <stdio.h>
#include <time.h>
#include <unistd.h>
 
int main(void)
{
   FILE *log = NULL;
   time_t start = 0;
   time_t stop = 0;
   time_t tdif = 0;
 while(1){
   time(&start);
   log=fopen("./log.txt","a");
 
   do{
      time(&stop);
      tdif=difftime(stop, start);
      printf(" %ld, localtime %s\n", tdif, asctime(localtime(&stop)));
      fprintf(log," %ld\n, localtime %s\n", tdif,asctime(localtime(&stop)));
      sleep(1);
   }
   while(tdif<32);
    
   fclose(log);
 }
   return 0;
}

Originally Posted by Salem

> I'm writing to a file because I don't have ssh when I shut down wifi for that one raspberry pi.
So how are you running your program from your ssh session?

If you're just putting it into the background using say
./myprog &

That isn't going to be enough if you then exit ssh.

You need this.
Linux nohup command help and examples

nohup ./myprog &

Yes, I did exactly that. I thought the program will continue runing after ssh pipe breaks. Of course, later I planned to start it at startup. I'll try this.

Seems to be working with nohup. I'll try a longer test.

Originally Posted by GhostLoveScore

This is your code, but I added endless while loop and print to file. It also stops working after about 15 minutes. gcc compiler.

I too do not use a Raspberry Pi system, don't know what O/S you are using, nor do I know why it should be ending after 15 minutes. Is there some power setting in the O/S that puts the O/S in sleep mode or shutting down the O/S?

Originally Posted by Salem

Does it work for more than 15 minutes logged in?

Signal Handler * Issue #6 * fivdi/pigpio * GitHub
> 2021-12-28 22:25:41 initInitialise: Can't lock /var/run/pigpio.pid
It looks like a resource leak of some kind, to the point you eventually run out of "something" and then it stops.

Yes, now it works fine for a couple of hours. I'm testing it again. Unfortunately, if it will crash, now it will crash after couple of hours.

I thought so too. It runs out of something. I've now updated my code so that I don't use pigpio library for serial communication. Instead I'm writing directly to port as described here ​Linux Serial Ports Using C/C++ | mbedded.ninja

Originally Posted by GhostLoveScore

Yes, now it works fine for a couple of hours. I'm testing it again. Unfortunately, if it will crash, now it will crash after couple of hours.

I thought so too. It runs out of something. I've now updated my code so that I don't use pigpio library for serial communication. Instead I'm writing directly to port as described here ​Linux Serial Ports Using C/C++ | mbedded.ninja

Have you tried to use vlagrind to detect any memory errors? You can write errors and warnings to a log file to examine after the program ends.