一个简单示例看懂.Net 并行编程

Posted 2020-09-20 微软专题

此示例尽量以最简洁的代码演示并行处理的功能，此示例代码中分别用单线程和多线程分别执行5次耗时1秒的操作。打印出执行过程及耗时。

以下为示例代码，.net framework要求4.0以上。

using System;
using System.Collections.Generic;
using System.Collections.Concurrent;
using System.Diagnostics;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;

namespace ParallelDemo
{

    class Program
    {
        static void Main(string[] args)
        {
            // First do the sequential version.
            Console.WriteLine("Executing sequential loop...");
            Stopwatch stopwatch = new Stopwatch();
            stopwatch.Start();

            //单线程执行
            for (int i = 0; i < 5; i++)
            {
                TestMethod();
            }

            stopwatch.Stop();
            Console.WriteLine("Sequential loop time in milliseconds: {0}", stopwatch.ElapsedMilliseconds);

            // Reset timer and results matrix. 
            stopwatch.Reset();

            Console.WriteLine("Executing parallel loop...");
            stopwatch.Start();
            //多线程执行
            Parallel.For(0, 5, i => TestMethod());
            stopwatch.Stop();
            Console.WriteLine("Parallel loop time in milliseconds: {0}", stopwatch.ElapsedMilliseconds);

            // Keep the console window open in debug mode.
            Console.WriteLine("Press any key to exit.");
            Console.ReadKey();
        }

        static void TestMethod()
        {
            var tid = Thread.CurrentThread.ManagedThreadId;
            Console.WriteLine("Thread {0} start", tid);
            Thread.Sleep(1000);
            Console.WriteLine("Thread {0} end", tid);
        }
    }

}

运行结果

Executing sequential loop...
Thread 9 start
Thread 9 end
Thread 9 start
Thread 9 end
Thread 9 start
Thread 9 end
Thread 9 start
Thread 9 end
Thread 9 start
Thread 9 end
Sequential loop time in milliseconds: 5004
Executing parallel loop...
Thread 9 start
Thread 10 start
Thread 11 start
Thread 12 start
Thread 13 start
Thread 9 end
Thread 10 end
Thread 11 end
Thread 12 end
Thread 13 end
Parallel loop time in milliseconds: 1024
Press any key to exit.

附：官方示例