矩阵乘法与线程和信号量

Question

我必须使用信号量实现与线程的矩阵乘法。问题是我不了解信号量是如何工作的，我的结果矩阵充满了零和程序挂起。你能解释一下我做错了吗？

这是我的代码：

class Program
{
    private static Semaphore semaphore = new Semaphore(0, 1);
    static void Main(string[] args)
    {
        int size;
        int[,] a = null, b = null, c = null;
        bool isNumeric;
        do
        {
            Console.Write("Insert size: ");
            isNumeric = int.TryParse(Console.ReadLine(), out size);
        }
        while (!isNumeric || size < 2);
        Console.WriteLine();
        SquareMatrix.Init(size, ref a);
        SquareMatrix.Init(size, ref b);
        SquareMatrix.Init(size, ref c);
        SquareMatrix.Fill(a);
        SquareMatrix.Fill(b);
        Console.WriteLine("Matrix 1:\n");
        SquareMatrix.Display(a);
        Console.WriteLine("Matrix 2:\n");
        SquareMatrix.Display(b);
        Console.WriteLine();
        DateTime start = DateTime.Now;
        for (int i = 0; i < size; i++)
        {
            Thread thread = new Thread(() => Multiply(i, size, a, b, c));
            thread.Name = i.ToString();
            thread.Start();
        }
        DateTime stop = DateTime.Now;
        Console.WriteLine("Result (" + (stop - start).TotalMilliseconds + " ms):\n");
        SquareMatrix.Display(c);
        Console.ReadLine();
    }
    public static void Multiply(int i, int size, int[,] a, int[,] b, int[,] c)
    {
        semaphore.WaitOne();
        for (int j = 0; j < size; j++)
        {
            c[i, j] = 0;
            for (int k = 0; k < size; k++)
            {
                c[i, j] += a[i, k] * b[k, j];
            }
        }
        semaphore.Release();
    }
}

和SquareMatrix代码：

static class SquareMatrix
{
    private static readonly Random random = new Random();
    public static void Init(int size, ref int[,] array)
    {
        array = new int[size, size];
    }
    public static void Fill(int[,] array)
    {
        for (int i = 0; i < array.GetLength(0); i++)
        {
            for (int j = 0; j < array.GetLength(0); j++)
            {

                array[i, j] = random.Next(-10, 10);
            }
        }
    }
    public static void Display(int[,] array)
    {
        string result = "";
        for (int i = 0; i < array.GetLength(0); i++)
        {
            for (int j = 0; j < array.GetLength(0); j++)
                result += array[i, j] + " ";
            result += "\n";
        }
        Console.Write(result + "\n");
    }
}