Question

I thought that the maximum user space for a 64bit process was 8TB, but I did a little test and the maximum I could get is 10-11GB.

Note: I don’t need that much memory in a process, I just want to understand why out of curiosity.

Here is my test program:

static void Main(string[] args)
{
    List<byte[]> list = new List<byte[]>();

    while (true)
    {
        Console.WriteLine("Press any key to allocate 1 more GB");
        Console.ReadKey(true);
        list.Add(new byte[1024 * 1024 * 1024]);

        Console.WriteLine("Memory size:");
        double memoryUsage = Process.GetCurrentProcess().PeakVirtualMemorySize64 / (double)(1024 * 1024 * 1024);
        Console.WriteLine(memoryUsage.ToString("0.00") + " GB");
        Console.WriteLine();
    }
}

EDIT:

Updated the test program to be more deterministic.

To accept an answer I would like to know how the real maximum allocated memory is calculated if 8TB is only theoretical.

Answer 1

It’s up to 8 TB, not 8 TB. You can potentially have up to 8 TB, but you need the matching RAM/swapfile.