Array.Copy --> 不支持大于 2GB 的数组

Question

我正在使用 Array.Copy Method (Array, Array, Int64)。我有以下静态方法

public static T[,] Copy<T>(T[,] a)
    where T : new()
{
    long n1 = a.GetLongLength(0);
    long n2 = a.GetLongLength(1);
    T[,] b = new T[n1, n2];
    System.Array.Copy(a, b, n1 * n2);
    return b;
}

和下面的代码来测试它

double[,] m1 = new double[46340, 46340];
double[,] m2 = Copy(m1); // works

double[,] m3 = new double[46341, 46341];
double[,] m4 = Copy(m3); // Arrays larger than 2GB are not supported
                         // length argument of Array.Copy

我知道 <gcAllowVeryLargeObjects enabled="true" /> 并且我已将其设置为 true。

我在Array.Copy Method (Array, Array, Int64)的文档中看到，对于长度参数有如下注释。

A 64-bit integer that represents the number of elements to copy. The integer must be between zero and Int32.MaxValue, inclusive.

我不明白为什么类型为Int64时参数长度有这个限制？有解决方法吗？是否计划在即将推出的 .net 版本中取消此限制？

Answer 1

解决方法可能是以下代码

public static T[,] Copy<T>(T[,] a)
    where T : new()
{
    long n1 = a.GetLongLength(0);
    long n2 = a.GetLongLength(1);
    long offset = 0;
    long length = n1 * n2;
    long maxlength = Int32.MaxValue;
    T[,] b = new T[n1, n2];
    while (length > maxlength)
    {
        System.Array.Copy(a, offset, b, offset, maxlength);
        offset += maxlength;
        length -= maxlength;
    }
    System.Array.Copy(a, offset, b, offset, length);
    return b;
}

其中数组被复制成大小为 Int32.MaxValue.

的块

Array.Copy --> 不支持大于 2GB 的数组

Array.Copy --> Arrays larger than 2GB are not supported

c#

arrays

multidimensional-array

.net-4.5

gcallowverylargeobjects