PLINQ测试结果

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 1     public class PLINQ
 2     {
 3         static int[] arr = Enumerable.Range(654321, 101010).ToArray();
 4 
 5         public static int _computeTimes = 0;
 6 
 7         public static void Test ()
 8         {
 9             Utils.Measure("Sequential", () =>
10             {
11                 bool[] results = new bool[arr.Length];
12                 for (int i = 0; i < arr.Length; i++)
13                 {
14                     results[i] = Utils.IsPrimeInt(arr[i]);
15                 }
16             });
17 
18             Utils.Measure("LINQ", () =>
19             {
20                 bool[] results = arr.
21                     Select(x => Utils.IsPrimeInt(x)).
22                     ToArray();
23             });
24 
25             Utils.Measure("PLINQ", () =>
26             {
27                 bool[] results = arr.AsParallel().AsOrdered().
28                     Select(x => Utils.IsPrimeInt(x)).
29                     ToArray();
30             });
31 
32             Console.WriteLine(_computeTimes.ToString());
33         }
34     }
35 
36     class Utils
37     {
38         public static void Measure ( string name, Action func )
39         {
40             Stopwatch stopwatch = new Stopwatch();
41             stopwatch.Start();
42             func();
43             stopwatch.Stop();
44             Console.WriteLine("-------------------------");
45             Console.WriteLine("" + name);
46             Console.WriteLine("      Time: " + stopwatch.ElapsedMilliseconds + " ms");
47             Console.WriteLine("-------------------------");
48 
49         }
50 
51         public static bool IsPrime ( long x )
52         {
53             if (x <= 2) 
54                 return x == 2;
55             if (x % 2 == 0) 
56                 return false;
57 
58             long sqrtx = (long)Math.Ceiling(Math.Sqrt(x));
59             for (long i = 3; i <= sqrtx; i++)
60             {
61                 if (x % i == 0) 
62                     return false;
63             }
64             return true;
65         }
66 
67 
68         public static bool IsPrimeInt ( int x )
69         {
70             if (x <= 2)
71                 return x == 2;
72             if (x % 2 == 0)
73                 return false;
74 
75             int sqrtx = (int)Math.Ceiling(Math.Sqrt(x));
76             for (int i = 3; i <= sqrtx; i++)
77             {
78                 //PLINQ._computeTimes = PLINQ._computeTimes + 1;
79                 if (x % i == 0)
80                     return false;
81             }
82             return true;
83         }
84 
85     }
Int32整数运算：
　　五百万到一千万左右运算速度区别不大
　　一千万以上PLINQ较快
Int64
　　三百万以上PLINQ较快
双核四线程处理器测试