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C# 並行編程之 PLINQ 基本使用

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C# 並行編程之 PLINQ 基本使用

PLINQ Summary

LINQ (LINQ) Language Integrated Query 可以方便的查詢並處理不同數據源的數據。PLINQ Parallel LINQ不光擁有LINQ的功能，還添加了並行操作的接口，以方便使用並提高效率。

一個簡單的例子

用一個簡單的例子足以說明PLINQ的使用。
簡單的說明：
第一部分：先在一個文檔中查詢包含字母 “a”的單詞首先使用 LINQ進行查詢10000次，然後使用PLINQ進行同樣的測試，看看效率有多少提高。 AsParallel() 是主要用到的接口。

第二部分：計算Short類型所有數字的和，同樣測試兩次使用LINQ和PLINQ。

第三部分：測試PLINQ的查找排序功能。使用的接口分別為AsOrdered()和orderby
AsOrdered：保持數據在數據源中的順序不變。
orderby：按用戶指定的順序進行排序，升序/降序

示例程序：

using System;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Diagnostics;
using System.Linq;
using System.IO;

namespace Sample6_1_plink_basic
{
    class Program
    {
        static int SumDefault(int[] array)
        {
            return array.Sum();
        }

        static int SumAsParallel(int[] array)
        {
            return array.AsParallel().Sum();
        }

        static string[] words = { Day, Car, Land, Road, Sea, Mountain, River};

        static void Main(string[] args)
        {
            var customers = System.IO.File.ReadAllLines(@D:	estdirCSParallel_ProgramSample6-1 plink basic	arget.txt);
            int nCounter = 0;
            Console.WriteLine(============================================================);
            Console.WriteLine(TEST NORMAL LINQ);
            Console.WriteLine(============================================================);
            var swatchpn = Stopwatch.StartNew();

            for (int i = 0; i < 10000; i++)
            {
                var normalkeyLetters = from line in customers
                                       let keys = line.Split(' ')
                                       from key in keys
                                       where (key.Contains('a'))
                                       select key;

                var normalkeyList = normalkeyLetters.ToList();
                nCounter = normalkeyList.Count();
            }

            swatchpn.Stop();
            Console.WriteLine(Word with letter a = {0}, nCounter);
            Console.WriteLine(LINQ Use Time: {0}, swatchpn.Elapsed);

            Console.WriteLine(

);
            Console.WriteLine(============================================================);
            Console.WriteLine(TEST PARALLEL LINQ);
            Console.WriteLine(============================================================);
            nCounter = 0;
            var swatchp = Stopwatch.StartNew();

            for (int i = 0; i < 10000; i++)
            {

                var keyLetters = from line in customers.AsParallel()
                                 let keys = line.Split(' ')
                                 from key in keys.AsParallel()
                                 where (key.Contains('a'))
                                 select key;

                var keyList = keyLetters.ToList();
                nCounter = keyList.Count();
            }

            swatchp.Stop();
            Console.WriteLine(Word with letter a = {0}, nCounter);
            Console.WriteLine(PLINQ Use Time: {0}, swatchp.Elapsed);

            // Generate array.
            int[] array = Enumerable.Range(0, short.MaxValue).ToArray();
            const int m = 10000;
            var s1 = Stopwatch.StartNew();
            for (int i = 0; i < m; i++)
            {
                SumDefault(array);
            }
            s1.Stop();

            var s2 = Stopwatch.StartNew();
            for (int i = 0; i < m; i++)
            {
                SumAsParallel(array);
            }
            s2.Stop();
            Console.WriteLine(

);
            Console.WriteLine(============================================================);
            Console.WriteLine(CALCULATE SUMMARY TEST);
            Console.WriteLine(============================================================);
            Console.WriteLine(Default Summary:  + ((double)(s1.Elapsed.TotalMilliseconds * 1000000) / m).ToString(0.00 ns));
            Console.WriteLine(Parallel Summary:  + ((double)(s2.Elapsed.TotalMilliseconds * 1000000) /m).ToString(0.00 ns));


            Console.WriteLine(

);
            Console.WriteLine(============================================================);
            Console.WriteLine(Parallel ASOrder Test);
            Console.WriteLine(============================================================);
            var orderwords = from word in words.AsParallel().AsOrdered()
                             where (word.Contains('a'))
                             select word;

            var orderletterList = orderwords.ToList();
            for (int i = 0; i < orderletterList.Count; i++)
            {
                Console.WriteLine(orderletterList[i]);
            }


            Console.WriteLine(

);
            Console.WriteLine(============================================================);
            Console.WriteLine(Parallel OrderBy Test);
            Console.WriteLine(============================================================);
            var orderbywords = from word in words.AsParallel()
                             where (word.Contains('a'))
                             orderby word ascending
                             select word;

            var orderbyletterList = orderbywords.ToList();
            for (int i = 0; i < orderbyletterList.Count; i++)
            {
                Console.WriteLine(orderbyletterList[i]);
            }

            Console.ReadKey();
        }
    }
}

測試結果：
這裡寫圖片描述