public static async Task <int[]> MergeSort_Recursive(int[] numbers, int threshold)
{
if (numbers.Length <= 1)
{
return(numbers);
}
int lengthLeft = numbers.Length / 2;
int lengthRight = numbers.Length - lengthLeft;
int[] leftResult;
int[] rightResult;
if (lengthLeft < threshold)
{
int[] left = new int[lengthLeft];
Array.Copy(numbers, left, lengthLeft);
leftResult = MergeSort_Serial.MergeSort_Recursive(left);
}
else
{
leftResult = await Task <int[]> .Run(async() =>
{
int[] left = new int[lengthLeft];
Array.Copy(numbers, left, lengthLeft);
return(await MergeSort_Recursive(left, threshold));
});
}
if (lengthRight < threshold)
{
int[] right = new int[lengthRight];
Array.Copy(numbers, lengthLeft, right, 0, lengthRight);
rightResult = MergeSort_Serial.MergeSort_Recursive(right);
}
else
{
rightResult = await Task <int[]> .Run(async() =>
{
int[] right = new int[lengthRight];
Array.Copy(numbers, lengthLeft, right, 0, lengthRight);
return(await MergeSort_Recursive(right, threshold));
});
}
return(Merge(leftResult, rightResult));
}
private static void MergeSort_Run(int[] numbers, int th1, int th2, int th3)
{
Stopwatch sw_serial = new Stopwatch();
sw_serial.Start();
var result_serial = MergeSort_Serial.MergeSort_Recursive(numbers);
sw_serial.Stop();
var serialTimeTaken = sw_serial.ElapsedMilliseconds;
Task[] tasks = new Task[4];
Stopwatch sw_parallel = new Stopwatch();
sw_parallel.Start();
int[] result_parallel;
long parallelTimeTaken = 0;
tasks[0] = MergeSort_Parallel.MergeSort_Recursive(numbers).ContinueWith(x =>
{
result_parallel = x.Result;
sw_parallel.Stop();
parallelTimeTaken = sw_parallel.ElapsedMilliseconds;
});
Task.WaitAll(tasks[0]);
Stopwatch sw_par_th1 = new Stopwatch();
sw_par_th1.Start();
int[] result_parallel_TH1;
long parallelTH1TimeTaken = 0;
tasks[1] = MergeSort_Parallel_TH.MergeSort_Recursive(numbers, th1).ContinueWith(x =>
{
result_parallel_TH1 = x.Result;
sw_par_th1.Stop();
parallelTH1TimeTaken = sw_par_th1.ElapsedMilliseconds;
});
Task.WaitAll(tasks[1]);
Stopwatch sw_par_th2 = new Stopwatch();
sw_par_th2.Start();
int[] result_parallel_TH2;
long parallelTH2TimeTaken = 0;
tasks[2] = MergeSort_Parallel_TH.MergeSort_Recursive(numbers, th2).ContinueWith(x =>
{
result_parallel_TH2 = x.Result;
sw_par_th2.Stop();
parallelTH2TimeTaken = sw_par_th2.ElapsedMilliseconds;
});
Task.WaitAll(tasks[2]);
Stopwatch sw_par_th3 = new Stopwatch();
sw_par_th3.Start();
int[] result_parallel_TH3;
long parallelTH3TimeTaken = 0;
tasks[3] = MergeSort_Parallel_TH.MergeSort_Recursive(numbers, th3).ContinueWith(x =>
{
result_parallel_TH3 = x.Result;
sw_par_th3.Stop();
parallelTH3TimeTaken = sw_par_th3.ElapsedMilliseconds;
});
Task.WaitAll(tasks[3]);
Console.WriteLine("MergeSort:\n\t Serial time taken: {0},\n\t Parallel time taken: {1},\n\t Parallel_TH-{2}: time taken: {3},\n\t Parallel_TH-{4}: time taken: {5},\n\t Parallel_TH-{6}: time taken: {7}", serialTimeTaken,
parallelTimeTaken, th1, parallelTH1TimeTaken, th2, parallelTH2TimeTaken, th3, parallelTH3TimeTaken);
}