Visual Studio 2010中Parallel类实现并行计算 软件测试
在.NET Framework 4.0中，在库的层次上，微软提供了大量的新内容来帮助程序员完成应用程序的并行化，其中包括Parallel LINQ，Task Parallel Library和Coordination Data Structures，这里我们就先来介绍一下最简单最常用的TPL。
将要跟随Visual Studio 2010一起发布的.NET Framework 4.0将包含很多基于库的对并行计算的支持，包括数据的并行化，任务的并行化等等，这一切都通过一个共同的工作调度器进行管理。
这些新的类型和类，将在System.Threading，System.Threading.Tasks，System.Linq和System.Collections.Concurrent这些名字空间中提供。通过这些新的类型和类，开发人员将无需面对如今复杂的多线程开发模式，而可以直接使用.NET Framework，更加高效简便地开发支持并行计算的应用程序，从而更加充分地利用多核CPU的优势，随着计算核心或者处理器的增加，以提升应用程序的性能。
而在.NET Framework中，Task Parallel Library (TPL)是其Parallel Extensions中一个重要组成部分，它提供了一种简便的多线程开发方式，通过它所提供的类或者函数，可以让程序员轻松地实现并行计算。其中，最简单的就是它的Parallel类
Parallel类
Parallel类就是TPL中的一个用于支持并行计算的类。Parallel类提供了诸多的静态函数，只需要简单的函数调用，我们就可以对常用的for循环，foreach循环进行并行化。下面我们通过一些实际的例子，来看看如何利用这个类将我们的应用程序并行化，以吃上多核这“免费的午餐”。
创建示例项目
为了演示如何将一个现有的项目并行化，我们需要先创建一个示例项目。在这个项目中，我们将模拟对数据的串行操作，然后介绍如何利用Parallel类将对数据的串行操作并行化，以充分利用多核CPU的优势，从而提升应用程序的性能。在Visual Studio 2010中，我们新创建一个Visual C#的控制台应用程序。然后在这个项目中添加一个类Employee，其实现代码如下：
using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace ParallelDemo { // 职员类 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; } // 模拟对数据的处理 public static decimal Process(Employee employee) { Console.WriteLine(”Processing {0}”, employee.EmployeeID); // 产生一个随机数 // 用以表示处理当前数据需要的时间 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; } } // 职员列表类 // 这是我们需要处理的数据 public class EmployeeList : List { public EmployeeList() { // 将职员添加到列表中 Add(new Employee { EmployeeID = 1, FirstName = “张”, 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 = “赵”, LastName = “匡胤”, HireDate = DateTime.Parse(”3/19/2000″) }); Add(new Employee { EmployeeID = 5, FirstName = “钱”, LastName = “进”, HireDate = DateTime.Parse(”7/17/2003″) }); Add(new Employee { EmployeeID = 6, FirstName = “孙”, LastName = “俊鹏”, 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 = “吴”, LastName = “明子”, HireDate = DateTime.Parse(”1/7/2008″) }); Add(new Employee { EmployeeID = 10, FirstName = “郑”, LastName = “邦万”, 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 = “冯”, LastName = “玛丽”, HireDate = DateTime.Parse(”7/19/2006″) }); Add(new Employee { EmployeeID = 13, FirstName = “陈”, LastName = “良乔”, HireDate = DateTime.Parse(”3/9/2001″) }); Add(new Employee { EmployeeID = 14, FirstName = “褚”, LastName = “春晖”, HireDate = DateTime.Parse(”7/15/2005″) }); Add(new Employee { EmployeeID = 15, FirstName = “卫”, LastName = “斯理”, HireDate = DateTime.Parse(”8/6/2003″) }); Add(new Employee { EmployeeID = 16, FirstName = “蒋”, 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 = “韩”, LastName = “斌”, HireDate = DateTime.Parse(”10/1/2006″) }); Add(new Employee { EmployeeID = 19, FirstName = “杨”, LastName = “雪”, HireDate = DateTime.Parse(”12/7/2002″) }); Add(new Employee { EmployeeID = 20, FirstName = “朱”, LastName = “辉”, HireDate = DateTime.Parse(”3/30/2001″) }); DateTime.Parse(”12/7/2002″) }); Add(new Employee { EmployeeID = 20, FirstName = “朱”, LastName = “辉”, HireDate = DateTime.Parse(”3/30/2001″) }); } } } } } }
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