Try the program to see what happens - would you expect a segmentation fault or OOM?

// File: HeapFunOOM-AllocationWithoutFree.cc


#include <iostream>


using namespace std;


int main() {

  cout << endl << "Let's Learn by Doing!" << endl;


  int *ptr_heap = NULL;  // sizeof(int) = 4

  // Allocate roughly 4GB of integers.

  int count_to_allocate = 1000000000;

  unsigned long total_allocation = 0;

  

  char user_choice;


  while (user_choice != 'N') {

    // TODO(1): Allocate without handling allocation failure.

    ptr_heap = new int[count_to_allocate];

    total_allocation += count_to_allocate * sizeof(int);


    // TODO(2): Uncomment code to allocate by handling failure.

    // You might have to comment above code.

    // try {

    //   ptr_heap = new int[count_to_allocate];

    //   total_allocation += count_to_allocate * sizeof(int);

    // } catch (const bad_alloc& e) {      

    //   cout << "Allocation failed: " << e.what() << endl;

    // }


    cout << "Allocated 4GB at " << ptr_heap

	 << "; Total allocation : " << total_allocation/1000000000 << " GB"

	 << "; Allocate more heap space? Y/N" << endl;


    // TODO: Uncomment to stop/observe heap growth of the program in procfs.

    // cin >> user_choice;

  }

}

You will see something like this

Seems like your program did throw an OOM error, but since it was handled, the OS terminated the process. However, in this case, you can ensure your program doesn’t crash if you handle std::bad_alloc case using a try/catch clause.

Try that out by commenting/uncommenting appropriate code in the program!