[解决]可以/我应该使用线程来从方法中产生结果吗？

问题描述：

我有一些代码可以从db消息队列中获取任务列表。并产生结果。这种运行速度很慢所以我想多线程。我怎样才能最好地实现这个的多线程版本：

Hi,

I have some code that gets a list of tasks from a db message queue. and yields results. This is running quite slowly so I want to multi-thread it. How can I best implement a multi-threaded version of this:

private IEnumerable<Data> GetData()
{
  while (!_cancel)
  {
     foreach (var dueMessage in F.MessageFactory.GetDueMessages())
     {
        var item = ProcessMessage(dueMessage);
        if (item != null)
        yield return item;
    }
  }
}

每个 F.MessageFactory.GetDueMessages（）可能有零到几百条消息在等待（在某些情况下，许多进程同时被安排）

理想情况下我希望每个 item 在准备就绪后立即生成，但消息（目前）仅在 ProcessMessage（dueMessage）中设置完成。

这意味着我必须为每个使用WaitHandle，而循环或者设置消息以便更早完成在这个过程中，~~就像 foreach 循环命中它一样。~~编辑：例如，只要 F。 MessageFactory.GetDueMessages（）返回列表。

所以，我的问题是：我怎样才能安全地多线程这个方法，同时让你产生结果很快？

谢谢大家^ _ ^

Andy

In each F.MessageFactory.GetDueMessages() there may be zero to hundreds of messages waiting (many processes are scheduled at the same time in some cases)

Ideally I would like each item to be yielded as soon as it is ready, but the message is (currently) only set to complete within ProcessMessage(dueMessage).

This means that I would either have to use a WaitHandle for each while loop or set the message to complete earlier in the process, ~~such as as soon as the foreach loop hits it.~~ such as as soon as F.MessageFactory.GetDueMessages() returns the list.

So, My question is: How can I safely multi-thread this method while yielding the results as soon as possible?

Thanks guys ^_^
Andy

答

编辑：我去的解决方案包括调整。

如果你按照评论，我的问题是有一次进程在我的ProcessMessage方法中占用所有时间。在我等待它做的时候我几乎无能为力，所以async并没有太大的改进。

我选择了Reactive Extension解决方案相反。

注意 - 我需要返回一个返回Enumberable 的方法。

The solution I went for including tweaks.

If you follow the comments, my issue is that there is once process that takes all the time in my ProcessMessage method. There is barely anything I can do while I'm waiting for it to do it's stuff so async was not much of an improvement.

I went for a Reactive Extension solution instead.

Note - I need to return a method that returns Enumberable.

        private void GetFlighData()
{
    while (!_cancel)
    {
        Parallel.ForEach(F.MessageFactory.GetDueMessages(), dueMessage =>
        {

            var item = ProcessMessage(dueMessage);
            if (item != null)
            {
                //Event instead of yield
                OnGetFlightData(item);
            }
        });
    }
}

private delegate void GetAFlightDataHandler(FlightData flightData);

private event GetAFlightDataHandler FlightData;

private void OnGetFlightData(FlightData flightData)
{
    if (FlightData != null)
        FlightData(flightData);
}

BackgroundWorker _worker = new BackgroundWorker();

//This is my property that returns a method.  It no longer returns GetFlightData but creates the method from observable.FromEvent
public override GetFlighDataMethod GetFlighDataMethod
{
    get
    {
        //Start the queue
        _worker.DoWork += delegate { GetFlighData(); };
        _worker.RunWorkerAsync();

        // create the method
        return () =>
        {
            var flightDataReceived = Observable.FromEvent<GetAFlightDataHandler, FlightData>(handler =>
            {
                GetAFlightDataHandler fdHandler = (e) =>
                {
                    handler(e);
                };
                return fdHandler;
            },
                fdHandler => FlightData += fdHandler,
                fdHandler => FlightData -= fdHandler
                );

            return flightDataReceived.ToEnumerable();
        };
    }
}

[解决]可以/我应该使用线程来从方法中产生结果吗？

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