Re: Dynamic multidimensional array, deallocation of pointer not malloced..

Hi all,

Having a problem with addressing large amounts of memory. I have a
simple piece of code here that is meant to allocate a large piece of
memory on a ppc64 machine. The code is:

/*
Test to see what happens when we try to allocate a massively huge
piece of memory.
*/

#include <iostream>
#include <string>
#include <stdexcept>
using namespace std;

int main(int argc, char** argv) {
  cout << "Attemping to allocate.." << endl;

  const int ROWS = 635000;
  const int COLS = 2350;

  // Allocate.
  try {
    int** test = new int*[ROWS];
    for (int i = 0; i < ROWS; i++) {
      test[i] = new int[COLS];
      for (int j = 0; j < COLS; j++) {
        test[i][j] = 0;
      }
    }

    cout << "Allocation succeeded!" << endl;
    cout << "Press a key to deallocate and continue.." << endl;
    string blank;
    getline(cin,blank);

    // Deallocate.
    for (int k = 0; k < ROWS; k++) {
      delete[] test[k];
    }
    delete[] test;

    cout << "Deallocation completed!" << endl;
    cout << "Press a key to terminate.." << endl;
    getline(cin,blank);
  }
  catch(bad_alloc& e) {
    cout << "Allocation failed.." << endl;
  }

  return 0;
}

If I set ROWS and COLS to 5000 and 5000, it works just fine. However,
if I set ROWS to 635000 and COLS to 2350, it will give me the
following error upon deallocation:

HugeMemory.exe(29468) malloc: *** Deallocation of a pointer not
malloced: 0x20afd2000; This could be a double free(), or free() called
with the middle of an allocated block; Try setting environment
variable MallocHelp to see tools to help debug

Note that the allocation step succeeds, and that I only receive this
error after allowing the code to deallocate the array.