當我使用:TPL似乎並沒有提高執行速度在MSDN例如
var queryA = from num in numberList.AsParallel()
select ExpensiveFunction(num); //good for PLINQ
var queryB = from num in numberList.AsParallel()
where num % 2 > 0
select num; //not as good for PLINQ
我的示例程序:
static void Main(string[] args)
{
// ThreadPool.SetMinThreads(100, 100);
var numberList = new List<int>();
for (int i = 0; i <= 1000; i++)
{
numberList.Add(i);
}
Stopwatch sw = new Stopwatch();
sw.Start();
var queryA = from num in numberList
select ExpensiveFunction(num); //good for PLINQ
var c = queryA.ToList<int>();
sw.Stop();
Console.WriteLine(sw.ElapsedMilliseconds);
sw.Reset();
sw.Start();
var queryB = from num in numberList.AsParallel()
select ExpensiveFunction(num); //good for PLINQ
c = queryB.ToList<int>();
sw.Stop();
Console.WriteLine(sw.ElapsedMilliseconds);
Console.ReadKey();
}
static int ExpensiveFunction(int a)
{
a = a + 100 - 9 + 0 + 98;
// Console.WriteLine(a);
return a;
}
結果是:
7
41
爲什麼使用AsParallel()
比不使用它慢?
'a + = 189;'是**不**昂貴的計算。 – spender