This programs takes a long time to close after the 'return;' on main()

Question

This is the code I am dealing with:

#include <iostream>
#include <map>

using namespace std;

static unsigned long collatzLength(unsigned long n) {
    static std::map<unsigned long,int> collatzMap;
    int mapResult = collatzMap[n];
    if (mapResult != 0) return mapResult;

    if (n == 1) {
        return 1;
    } else { 
        collatzMap[n] = 1 + collatzLength(n%2==0?n/2:3*n+1);
        return collatzMap[n];
    }
}

int main() {
    int maxIndex = 1;
    unsigned int max = 1;
    for (int i=1; i<1000000; i++) {
        //cout<<i<<endl;
        unsigned long count = collatzLength(i);
        if (count > max) {
            maxIndex = i;
            max = count;
        }
    }
    cout<<maxIndex<<endl;
    getchar();
    cout<<"Returning..."<<endl;
    return maxIndex;
}

When I compile and run this program (using Visual Studio 2012 and Release build settings) it takes like 10 seconds (on my computer) to close after the program prints "Returning..."

Why is that?

Note: I am aware that this program is bad written and that i probably shouldn't be using 'static' on the collatzLength nor using a cache for that function, but I am not interesting on how to make this code better, I am just interesting about why does it take so much to close.

Answer 1

Go to project settings on your start up project, Debugging section. Enter _NO_DEBUG_HEAP=1 into the Environment section. You need to do this even in Release mode.