使用内存映射 IO 文件时遇到过多的内存不足异常

问：

我正在尝试创建内存映射的 IO 文件，以调整大小 （1-100 GB） 文件。这些文件将包含在此过程中生成的随机数据。

因此，我尝试通过考虑系统的可用内存来动态生成分区。

以下是源代码。

public class RandomLinesGenerator
{
    private static string GenerateRandomTextLine(int minValue, int maxValue)
    {
        const string chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
        Random random = new Random();
        int length = random.Next(minValue, maxValue);

        return new string(Enumerable.Repeat(chars, length)
          .Select(s => s[random.Next(s.Length)]).ToArray());
    }

    public static byte[] GetRandomBytes(long desiredByteCount, int prefixIntMinValue, int prefixIntMaxValue)
    {
        Random random = new Random();

        long currentByteCount = 0;

        StringBuilder builder = new StringBuilder();

        while (currentByteCount < desiredByteCount)
        {
            // Generate a random integer
            int randomNumber = random.Next(prefixIntMinValue, prefixIntMaxValue + 1);

            // Generate a random line
            string randomLine = $"{randomNumber} {GenerateRandomTextLine(1, 150)}";

            // Calculate the byte count of the line
            long lineByteCount = Encoding.UTF8.GetByteCount(randomLine) + Environment.NewLine.Length;

            // If adding the line exceeds the desired byte count, break the loop
            if (currentByteCount + lineByteCount > desiredByteCount)
            {
                break;
            }

            builder.AppendLine(randomLine); // ==> This is the line where the exception is occurring of Insufficient memory..

            currentByteCount += lineByteCount;
        }

        var bytes =  Encoding.UTF8.GetBytes(builder.ToString());
        builder.Clear();

        return bytes;
    }
}

public class MemoryMappedIOTechnique
{
    private static readonly string _fileLocation = Path.Combine("Resources", "files");
    private long GetPartitionSize(long totalFileSize)
    {
        var partitionSize = (long)Math.Ceiling((long)new PerformanceCounter("Memory", "Available Bytes").NextValue() * 0.8);
        return Math.Min(partitionSize ,totalFileSize);
    }

    public void Execute(int sizeInGb)
    {
        try
        {    

            long totalBytesToWrite = sizeInGb * Convert.ToInt64(1024 * 1024 * 1024);

            string filePath = Path.Combine(_fileLocation, $"file_{sizeInGb}-GB.txt");
            long partitionSize = GetPartitionSize(totalBytesToWrite);

            using (MemoryMappedFile mmf = MemoryMappedFile.CreateFromFile(filePath, FileMode.Create, "mmf", totalBytesToWrite))
            {
                long offset = 0;
                long partitions = (totalBytesToWrite / partitionSize);

                for (var partition = 0; partition < partitions; partition++)
                {
                    using (var accessor = mmf.CreateViewAccessor(offset, partitionSize))
                    {
                        var randomBytes = RandomLinesGenerator.GetRandomBytes(partitionSize, 10, 2500);
                        accessor.WriteArray(0, randomBytes, 0, randomBytes.Length);
                        offset += partitionSize;
                    }
                }
            }
        }
        catch(Exception ex)
        {

        }
    }

现在，当我刚刚调用提供 2 GB 的函数时，我遇到了异常。首先，它花费了更多的时间，另一个是导致“内存不足”的异常 我可以看到在任务管理器上，几乎 3 GB 仍然可用。

谁能指导我如何更改源代码以安全地处理所有类型的情况，而不会出现内存不足的异常情况？需要生成 （ 1， 2， ...-100 GB ） 文件。

我对内存映射 IO 完全陌生，对整个主题知之甚少。