如何并行和串行地处理集合中的项目 [英] How to process items in collection parallely and serially both

问题描述

我有一个集合，其中包含要处理的元素，最多只能一起处理四个元素.在运行时，所有进程一起启动，并且都进入等待状态.一次只处理四个元素.

I have a collection which has elements to be processed and at max only four elements can be processed together. At run time all process started together and all goes in waiting state. Only four elements are processed at one time.

问题是处理元素是随机选择的，因为所有线程都在等待资源释放.意味着第一个元素可以是集合中的最后一个元素.

Problem is the processing elements are chosen randomly as all threads are waiting for resources to get free. Means first element can be the last one from collection.

但是，我需要处理元素以便它们在集合中.

But, I need to process elements in order they are in the collection.

请告诉我如何实现?

我正在使用TPL和C#4.0

I am using TPL and C# 4.0

推荐答案

这是我实现此任务的方式

This is how I acheived this task

public delegate void ProcessFinished(IParallelProcess process);
public interface IParallelProcess
{
    void Start();
    event ProcessFinished ProcessFinished;
}

public class ParallelProcessBasket : ConcurrentQueue<IParallelProcess>
{
    public void Put(IParallelProcess process)
    {
        base.Enqueue(process);
    }
    public IParallelProcess Get()
    {
        IParallelProcess process = null;
        base.TryDequeue(out process);
        return process;
    }
}
public class ParallelProcessor<T> where T : class
{
    private ParallelProcessBasket basket;
    private readonly int MAX_DEGREE_OF_PARALLELISM;
    private Action<T> action;
    public ParallelProcessor(int degreeOfParallelism, IEnumerable<IParallelProcess> processes, Action<T> action)
    {
        basket = new ParallelProcessBasket();
        this.action = action;
        processes.ToList().ForEach(
            (p) =>
            {
                basket.Enqueue(p);
                p.ProcessFinished += new ProcessFinished(p_ProcessFinished);
            });
        MAX_DEGREE_OF_PARALLELISM = degreeOfParallelism;
    }

    private void p_ProcessFinished(IParallelProcess process)
    {
        if (!basket.IsEmpty)
        {
            T element = basket.Get() as T;
            if (element != null)
            {
                Task.Factory.StartNew(() => action(element));
            }
        }
    }


    public void StartProcessing()
    {
        // take first level of iteration
        for (int cnt = 0; cnt < MAX_DEGREE_OF_PARALLELISM; cnt++)
        {
            if (!basket.IsEmpty)
            {
                T element = basket.Get() as T;
                if (element != null)
                {
                    Task.Factory.StartNew(() => action(element));
                }
            }
        }
    }
}
static void Main(string[] args)    
{
     ParallelProcessor<ParallelTask> pr = new ParallelProcessor<ParallelTask>(Environment.ProcessorCount, collection, (e) => e.Method1());
            pr.StartProcessing();
}

谢谢..

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