Question

I have a fairly large, fairly simple, array that’s tracking 750,000 entries. In 64-bit .NET it works fine; however on the 32-bit client it’s failing with an OutOfMemory exception. I know I’m not running out of memory. The client needing this program, cannot use the 64-bit version.

The following pseudo code compiles (edit: the original code did not compile due to a typo, this has been fixed) and, throws the same exception, when targeting the x86 architecture, on two machines:

• A Windows XP, 32-bit machine, running 4 GB of RAM and .NET Framework 4
• A Windows 7, 64-bit machine, running 8 GB of RAM and .NET Framework 4

Edit: Switching the compiler flag to explicitly to target the x64 architecture allows it to run on the Windows 7, 64-bit machine.

using System;

public class Storage
{
    Storage futureStorage;
    int count;
    int years;
    bool isTest;
    bool isSet;
}

public static class Program
{
    public static void Main()
    {
        Storage[] storageArray = new Storage[750000];
        for (int i = 0; i < 750000; i++)
        {
            storageArray[i] = new Storage();
        }
    }
}

---

Edit:

The network this code is running on is a closed network, no external network connection, so posting more exact code and relevant exception details is a bit more of a process that I am working on. I do have intellitrace running, with full debug symbols and a few compiler switches, more details to follow as soon as I port it over to an internet connected network.

---

On both machines, the code bombs out around an index of 693,000 (693,002 on XP, 693,646 on Windows 7 to be exact).

Anyone have any ideas as to what the issue might be? When I do a dump and profile after the code, I’m barely using 25 MB of RAM.

I’d switch to unsafe/unmanaged if it buys me anything, but the only attempt I’ve made at it makes me unable to use my Storage class.

Update:

Seems several folks are unable to replicate the issue (including myself on a different machine/network).

However, I came up with a solution (using LINQ) that eases the problem, it only throws the exception 1/5 times or so now, anyone know if there’s any issues or caveats I should be aware of using this solution, and why internally it might work compared to the other one?

using System;
using System.Linq;    

public class Storage
{
    Storage futureStorage;
    int count;
    int years;
    bool isTest;
    bool isSet;
}

public static class Program
{
    public IEnumerable<Storage> storageEnumerable;
    public static void Main()
    {
        storageEnumerable = (from x in  Enumerable.Range(0, 750000) select new Storage() {count = x});
        foreach (Storage s in storageEnumerable)
            Console.WriteLine(x);
    }
}

The above LINQ code uses far less memory, but the exception still occurs; and only on machines in this network, not on other machines outside of the network (or within an IIS application pool for that matter).

Considering other users have since reported not being able to reproduce the bug, it seems to possibly be environment or hardware specific. Could there be a network monitoring tool, or anti-virus program triggering on these two code implementations? If so, is there a better/recommended way to initialize the array so that I avoid that?

Answer 1

Maybe this will help?

What is the Maximum Size that an Array can hold?

The answer says maybe using List may use less memory.