.Net(C#) Parallel.For和Parallel.Invoke介绍及使用方法

1、Parallel.For()方法

Parallel.For(intfromInclude,inttoExclude,Action<int>body)

与for循环类似，执行并行的循环，相当于每次循环一个线程

官方文档：https://docs.microsoft.com/zh-cn/dotnet/api/system.threading.tasks.parallel.for?redirectedfrom=MSDN&view=netframework-4.7.2

Parallel.For(0,10,(i)=>{
Console.Write(i);
});

完整示例代码：

using System;
using System.Threading;
using System.Threading.Tasks;
public >Example
{
   public static void Main()
   {
      var rnd = new Random();
      int breakIndex = rnd.Next(1, 11);
      Nullable<long> lowest = new Nullable<long>();
      Console.WriteLine("Will call Break at iteration {0}\n",
                        breakIndex);
      var result = Parallel.For(1, 101, (i, state) => {
                                            Console.WriteLine("Beginning iteration {0}", i);
                                            int delay;
                                            Monitor.Enter(rnd);
                                               delay = rnd.Next(1, 1001);
                                            Monitor.Exit(rnd);
                                            Thread.Sleep(delay);
                                            
                                            if (state.ShouldExitCurrentIteration) {
                                               if (state.LowestBreakIteration < i)
                                                  return;
                                            }
                                            if (i == breakIndex) {
                                               Console.WriteLine("Break in iteration {0}", i);
                                               state.Break();
                                               if (state.LowestBreakIteration.HasValue)
                                                  if (lowest < state.LowestBreakIteration)
                                                     lowest = state.LowestBreakIteration;
                                                  else
                                                     lowest = state.LowestBreakIteration;
                                            }
                                            Console.WriteLine("Completed iteration {0}", i);
                                       });
         if (lowest.HasValue)
            Console.WriteLine("\nLowest Break Iteration: {0}", lowest);
         else
            Console.WriteLine("\nNo lowest break iteration.");
   }
}

2、Parallel.Invoke()方法

Parallel.Invoke(ParallelOptions,Action[])

对给定任务实现并行执行

官方文档：https://docs.microsoft.com/zh-cn/dotnet/api/system.threading.tasks.parallel.invoke?redirectedfrom=MSDN&view=netframework-4.7.2

varall=new[]{0,1,2,3,4,5,6,7,8,9};
Parallel.ForEach(all,(i)=>{
Console.Write($"{i}");
});

完整示例代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
    >ParallelInvokeDemo
    {

        //显示功能:

        // Parallel.Invoke()

        //预期结果:

        //执行每个任务的线程可能不同。

        //线程分配在不同的执行中可能不同。

        //这些任务可以按任何顺序执行。

        //文档:

        // http://msdn.microsoft.com/library/dd783942(VS.100). aspx
        static void Main()
        {
            try
            {
                Parallel.Invoke(
                    BasicAction,	// Param #0 - static method
                    () =>			// Param #1 - lambda expression
                    {
                        Console.WriteLine("Method=beta, Thread={0}", Thread.CurrentThread.ManagedThreadId);
                    },
                    delegate()		// Param #2 - in-line delegate
                    {
                        Console.WriteLine("Method=gamma, Thread={0}", Thread.CurrentThread.ManagedThreadId);
                    }
                );
            }
	//本例中不期望出现异常，但如果仍然从任务中抛出异常，
        //它将被包装在AggregateException中，并传播到主线程。
            catch (AggregateException e)
            {
                Console.WriteLine("An action has thrown an exception. THIS WAS UNEXPECTED.\n{0}", e.InnerException.ToString());
            }
        }
        static void BasicAction()
        {
            Console.WriteLine("Method=alpha, Thread={0}", Thread.CurrentThread.ManagedThreadId);
        }

    }

注意：所有的并行开发不是简单的以为只要将For换成Parallel.For或调用Parallel.Invoke()执行任务这样简单。