C++ (cilk plus code): Segmentation fault 11

Question

I downloaded Intel Parallel Studio and then went to the command and entered:

source /opt/intel/bin/compilervars.sh intel64

followed by: icpc file.cpp to run a Cilk plus file.

The file.cpp is a simplified version of an original example used in cilkplus.org so it should work but it produces a segmentation fault

here's the file I'm trying to run using cilk plus compiler:

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

int fib(int n)
{
    if (n < 2)
        return n;
    int x = cilk_spawn fib(n-1);
    int y =  fib(n-2);
    cilk_sync;
    return x + y;
}

int main(int argc, char *argv[])
{
    int n = 39;

    clock_t start = clock();
    int result = fib(n);
    clock_t end = clock();

    double duration = (double)(end - start) / CLOCKS_PER_SEC;
    printf("Calculated in %.3f seconds using %d workers.\n", duration, __cilkrts_get_nworkers());


    return 0;
}

Answer 1

I think the problem is 39.

The code looks right to me. While I have never worked with cilk, yet from what I get the code seems right considering you did copy it.

My guess would be 39 is a number too big. Try smaller or bigger numbers.

If it works, remove all the duration nonsense and try a loop for fib(i) for first 40 cases. Use the simpler version before you mess it up.