How to keep forking a process until I "almost" run out of memory

Question

I want to keep forking a process until I'm almost out memory. How Do I know how many times I can fork a process without crashing?

Answer 1

Here is program to calculate estimate (using Linux API's):

#include <sys/resource.h>
#include <sys/sysinfo.h>
#include <stdio.h>

unsigned long maxmem() {
    struct sysinfo info;
    if (sysinfo(&info) < 0)
        return 0;
    return info.freeram;
}

long getmem(void) {
    struct rusage r_usage;
    getrusage(RUSAGE_SELF,&r_usage);
    return r_usage.ru_maxrss;
}

int main() {
    printf("Can fork %d times. Mfm: %d, upp: %d\n", maxmem() / 1024 / getmem(), maxmem() / 1024, getmem());
    return 0;
}

Please note that this is just an estimate, you may need to run this code inside your application when it reaches peak memory usage.