在 C# 中正确使用 Parallel for 循环?

问题描述

在此示例中，如果我想将可以执行函数 DoWork 的线程数限制为 10 处，这是 Parallel.For 循环的正确使用吗?一次?在十个线程之一可用之前，其他线程是否会被阻塞?如果没有，什么是更好的多线程解决方案，它仍然可以让我执行该函数 6000 多次?

In this example, is this the correct use of the Parallel.For loop if I want to limit the number of threads that can perform the function DoWork to ten at a time? Will other threads be blocked until one of the ten threads becomes available? If not, what is a better multi-threaded solution that would still let me execute that function 6000+ times?

class Program
{
    static void Main(string[] args)
    {
        ThreadExample ex = new ThreadExample();
    }
}

public class ThreadExample
{
    int limit = 6411;

    public ThreadExample()
    {
        Console.WriteLine("Starting threads...");
        int temp = 0;
        Parallel.For(temp, limit, new ParallelOptions { MaxDegreeOfParallelism = 10 }, i =>
        {
            DoWork(temp);
            temp++;
        });
    }

    public void DoWork(int info)
    {
        //Thread.Sleep(50); //doing some work here.

        int num = info * 5;

        Console.WriteLine("Thread: {0}      Result: {1}", info.ToString(), num.ToString());
    }
}

推荐答案

您需要使用传递给 lambda 函数的 i 作为索引.Parallel.For 使您免于使用循环计数器的麻烦，但您需要使用它！

You need to use the i passed to the lambda function as index. Parallel.For relieves you from the hassle of working with the loop counter, but you need to use it!

    Parallel.For(0, limit, new ParallelOptions { MaxDegreeOfParallelism = 10 }, i =>
    {
        DoWork(i);
    });

至于您的其他问题:

• 是的，这将正确限制同时工作的线程数量.
• 没有线程被阻塞.迭代会排队，一旦有线程可用，它就会从队列中进行下一次迭代(以同步方式)进行处理.

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