Endless malloc

.gitignore

/mallocx

Makefile

all: mallocx

mallocx: mallocx.c
	cc -o mallocx mallocx.c

clean:
	rm -f mallocx

mallocx.c

// Allocate until machine runs out of memory. Virtual memory is different from
// physical.
//
//    $ make
//    $ ./mallocx
//       1000000            10485760000000
//       2000000            20971520000000
//       3000000            31457280000000
//       4000000            41943040000000
//       5000000            52428800000000
//       6000000            62914560000000
//       7000000            73400320000000
//       8000000            83886080000000
//       9000000            94371840000000
//      10000000           104857600000000
//      11000000           115343360000000
//      12000000           125829120000000
//      13000000           136314880000000
//    mallocx(21718,0x7fff77527000) malloc: *** mach_vm_map(size=10485760) failed (error code=3)
//    *** error: can't allocate region
//    *** set a breakpoint in malloc_error_break to debug
//    131063.58GB
//
// On my old Macbook Pro with 16GB RAM, OS X can allocate ~127TB virtual memory
// before bailing out.
//
// More: http://cecs.wright.edu/~pmateti/Courses/233/Labs/Processes/virtualMemory.html

#include <stdlib.h>
#include <stdio.h>

// MB
const long MB = 1024 * 1024;
// GB
const long GB = 1024 * 1024 * 1024;
// allocation increment
const int increment = 10 * MB;

int main(int argc, char const *argv[])
{
    unsigned long i = 0;
    while (1) {
        int *p = malloc(increment);
        if (p == NULL) {
            fprintf(stderr, "%0.2fGB\n", (double)(i * increment) / GB);
            break;
        }
        i++;
        if (i % 1000000 == 0) {
            printf("%10lu\t%20lu\n", i, i * increment);
        }
    }
}