Visual Studio 2010中Parallel類實(shí)現(xiàn)并行計(jì)算
將要跟隨Visual Studio 2010一起發(fā)布的.NET Framework 4.0將包含很多基于庫的對(duì)并行計(jì)算的支持，包括數(shù)據(jù)的并行化，任務(wù)的并行化等等，這一切都通過一個(gè)共同的工作調(diào)度器進(jìn)行管理。
這些新的類型和類，將在System.Threading，System.Threading.Tasks，System.Linq和System.Collections.Concurrent這些名字空間中提供。通過這些新的類型和類，開發(fā)人員將無需面對(duì)如今復(fù)雜的多線程開發(fā)模式，而可以直接使用.NET Framework，更加高效簡便地開發(fā)支持并行計(jì)算的應(yīng)用程序，從而更加充分地利用多核CPU的優(yōu)勢，隨著計(jì)算核心或者處理器的增加，以提升應(yīng)用程序的性能。
而在.NET Framework中，Task Parallel Library (TPL)是其Parallel Extensions中一個(gè)重要組成部分，它提供了一種簡便的多線程開發(fā)方式，通過它所提供的類或者函數(shù)，可以讓程序員輕松地實(shí)現(xiàn)并行計(jì)算。其中，最簡單的就是它的Parallel類
Parallel類
Parallel類就是TPL中的一個(gè)用于支持并行計(jì)算的類。Parallel類提供了諸多的靜態(tài)函數(shù)，只需要簡單的函數(shù)調(diào)用，我們就可以對(duì)常用的for循環(huán)，foreach循環(huán)進(jìn)行并行化。下面我們通過一些實(shí)際的例子，來看看如何利用這個(gè)類將我們的應(yīng)用程序并行化，以吃上多核這“免費(fèi)的午餐”。
創(chuàng)建示例項(xiàng)目
為了演示如何將一個(gè)現(xiàn)有的項(xiàng)目并行化，我們需要先創(chuàng)建一個(gè)示例項(xiàng)目。在這個(gè)項(xiàng)目中，我們將模擬對(duì)數(shù)據(jù)的串行操作，然后介紹如何利用Parallel類將對(duì)數(shù)據(jù)的串行操作并行化，以充分利用多核CPU的優(yōu)勢，從而提升應(yīng)用程序的性能。在Visual Studio 2010中，我們新創(chuàng)建一個(gè)Visual C#的控制臺(tái)應(yīng)用程序。然后在這個(gè)項(xiàng)目中添加一個(gè)類Employee，其實(shí)現(xiàn)代碼如下：
- using System;
- using System.Collections.Generic;
- using System.Linq;
- using System.Text;
- namespace ParallelDemo
- {
- // 職員類
- public class Employee
- {
- public string FirstName
- {
- get;
- set;
- }
- public string LastName
- {
- get;
- set;
- }
- public string Address
- {
- get;
- set;
- }
- public DateTime HireDate
- {
- get;
- set;
- }
- public int EmployeeID
- {
- get;
- set;
- }
- // 模擬對(duì)數(shù)據(jù)的處理
- public static decimal Process(Employee employee)
- {
- Console.WriteLine(”Processing {0}”, employee.EmployeeID);
- // 產(chǎn)生一個(gè)隨機(jī)數(shù)
- // 用以表示處理當(dāng)前數(shù)據(jù)需要的時(shí)間
- var rand = new Random(DateTime.Now.Millisecond);
- var delay = rand.Next(1, 5);
- var count = 0;
- var process = true;
- while (process)
- {
- System.Threading.Thread.Sleep(1000);
- count++;
- if (count >= delay)
- process = false;
- }
- return delay;
- }
- }
- // 職員列表類
- // 這是我們需要處理的數(shù)據(jù)
- public class EmployeeList : List
- {
- public EmployeeList()
- {
- // 將職員添加到列表中
- Add(new Employee { EmployeeID = 1, FirstName = “張”, LastName = “三”, HireDate = DateTime.Parse(”1/1/2007″) });
- Add(new Employee { EmployeeID = 2, FirstName = “李”, LastName = “四”, HireDate = DateTime.Parse(”3/15/2006″) });
- Add(new Employee { EmployeeID = 3, FirstName = “王”, LastName = “麻子”, HireDate = DateTime.Parse(”6/17/2005″) });
- Add(new Employee { EmployeeID = 4, FirstName = “趙”, LastName = “匡胤”, HireDate = DateTime.Parse(”3/19/2000″) });
- Add(new Employee { EmployeeID = 5, FirstName = “錢”, LastName = “進(jìn)”, HireDate = DateTime.Parse(”7/17/2003″) });
- Add(new Employee { EmployeeID = 6, FirstName = “孫”, LastName = “俊鵬”, HireDate = DateTime.Parse(”9/13/2005″) });
- Add(new Employee { EmployeeID = 7, FirstName = “李”, LastName = “明”, HireDate = DateTime.Parse(”12/3/2002″) });
- Add(new Employee { EmployeeID = 8, FirstName = “周”, LastName = “大勇”, HireDate = DateTime.Parse(”7/1/2008″) });
- Add(new Employee { EmployeeID = 9, FirstName = “吳”, LastName = “明子”, HireDate = DateTime.Parse(”1/7/2008″) });
- Add(new Employee { EmployeeID = 10, FirstName = “鄭”, LastName = “邦萬”, HireDate = DateTime.Parse(”11/1/2001″) });
- Add(new Employee { EmployeeID = 11, FirstName = “王”, LastName = “朝”, HireDate = DateTime.Parse(”4/21/2006″) });
- Add(new Employee { EmployeeID = 12, FirstName = “馮”, LastName = “瑪麗”, HireDate = DateTime.Parse(”7/19/2006″) });
- Add(new Employee { EmployeeID = 13, FirstName = “陳”, LastName = “良喬”, HireDate = DateTime.Parse(”3/9/2001″) });
- Add(new Employee { EmployeeID = 14, FirstName = “褚”, LastName = “春暉”, HireDate = DateTime.Parse(”7/15/2005″) });
- Add(new Employee { EmployeeID = 15, FirstName = “衛(wèi)”, LastName = “斯理”, HireDate = DateTime.Parse(”8/6/2003″) });
- Add(new Employee { EmployeeID = 16, FirstName = “蔣”, LastName = “中正”, HireDate = DateTime.Parse(”5/18/2005″) });
- Add(new Employee { EmployeeID = 17, FirstName = “沈”, LastName = “洋洋”, HireDate = DateTime.Parse(”8/5/2002″) });
- Add(new Employee { EmployeeID = 18, FirstName = “韓”, LastName = “斌”, HireDate = DateTime.Parse(”10/1/2006″) });
- Add(new Employee { EmployeeID = 19, FirstName = “楊”, LastName = “雪”, HireDate = DateTime.Parse(”12/7/2002″) });
- Add(new Employee { EmployeeID = 20, FirstName = “朱”, LastName = “輝”, HireDate = DateTime.Parse(”3/30/2001″) });
- DateTime.Parse(”12/7/2002″) });
- Add(new Employee { EmployeeID = 20, FirstName = “朱”, LastName = “輝”, HireDate = DateTime.Parse(”3/30/2001″) });
- }
- }
- }
- }
- }
- }
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