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c - Do sleep functions sleep all threads or just the one who call it?

I am programming with pthread on linux(Centos)? I wanna to threads sleep a short time to wait for something. I am trying to use sleep(), nanosleep(), or usleep() or maybe something can do that. I want to ask that: Do sleep functions sleep all threads or just the one who call it? Any advices or references would be appreciate.

void *start_routine () {
    /* I just call sleep functions here */
    sleep (1); /* sleep all threads or just the one who call it? 
                  what about nanosleep(), usleep(), actually I 
                  want the threads who call sleep function can 
                  sleep with micro-seconds or mili-seconds.  
               */
    ...
}

int main (int argc, char **argv) {
    /* I just create threads here */
    pthread_create (... ...);
    ...
    return 0;
}

My test program:

#define _GNU_SOURCE
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <sched.h>
#include <unistd.h>

void *start_routine (void *j) {

    unsigned long sum;
    int i;
    int jj;
    jj = (int)j;
    do {
        sum = 1;
        for (i=0; i<10000000; i++) {
            sum = sum * (sum+i);
        }
        if (jj == 0) {
            printf ("33[22;33m[jj%d.%ld]", jj, sum);
            sleep(1);           
        }
        else {
            printf ("33[22;34m[jj%d.%ld]", jj, sum);
        }

    }while (1);

    pthread_exit((void *)0);
}
int main(int argc, char *argv[])
{
    cpu_set_t cpuset;
    pthread_t thread[2];
    int i;
    i = 0;
    CPU_ZERO(&cpuset);
    CPU_SET(i, &cpuset);

    pthread_create (&thread[0], NULL, start_routine, (void *)i);
    pthread_setaffinity_np(thread[0], sizeof(cpu_set_t), &cpuset);
    i = 1;
    CPU_ZERO(&cpuset);
    CPU_SET(i, &cpuset);
    pthread_create (&thread[1], NULL, start_routine, (void *)i);
    pthread_setaffinity_np(thread[1], sizeof(cpu_set_t), &cpuset);
    pthread_exit (NULL);
}
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1 Answer

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by (71.8m points)

The standard spells it:

The sleep() function shall cause the calling thread to be suspended from execution until ....

The linux one is just as clear:

sleep() makes the calling thread sleep until...

There are however a few erroneous references which maintain otherwise. linux.die.net used to state sleep causes the process to wait.


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