结合PLINQ和Async方法 [英] Combining PLINQ with Async method

问题描述

我试图像这样组合我的PLINQ语句:

I'm trying to combine my PLINQ statement like this:

Enumerable.Range(0, _sortedList.Count()).AsParallel().WithDegreeOfParallelism(10)
          .Select(i =>  GetTransactionDetails(_sortedList[i].TransactionID))
          .ToList();

使用这样的异步方法:

 private async void GetTransactionDetails(string _trID)
 {
      await Task.Run(() =>
      {
      });
 }

这样我就可以在这里简单地添加一个await运算符:

So that I can simply add an await operator in here:

 Enumerable.Range(0, _sortedList.Count()).AsParallel().WithDegreeOfParallelism(10)
           .Select(i => await GetTransactionDetails(_sortedList[i].TransactionID))
           .ToList();

我该如何实现?

P.S.这样，我可以同时发出5-10个HTTP请求，同时确保最终用户在这样做时不会感到任何屏幕"冻结...

P.S. This way I could make 5-10 HTTP requests simultaneously while ensuring that the end user doesn't feels any "screen" freezing while doing so...

推荐答案

您可以采取几种方法.

首先，更正确"的方法(这也是更多的工作).将GetTransactionDetails设置为正确的async方法(即，不使用Task.Run):

First, the "more correct" approach (which is also more work). Make GetTransactionDetails into a proper async method (i.e., does not use Task.Run):

private async Task GetTransactionDetailsAsync(string _trID);

然后您可以同时调用该方法:

Then you can call that method concurrently:

var tasks = _sortedList.Select(x => GetTransactionDetailsAsync(x.TransactionID));
await Task.WhenAll(tasks);

如果需要限制并发性，请使用SemaphoreSlim.

If you need to limit concurrency, use a SemaphoreSlim.

第二种方法比较浪费(就线程使用而言)，但是鉴于我们已经看到了代码的哪些部分，第二种方法可能会更容易.第二种方法是使所有I/O保持同步，并以常规PLINQ方式进行:

The second approach is more wasteful (in terms of thread usage), but is probably easier given what parts of your code we've seen. The second approach is to leave the I/O all synchronous and just do it in a regular PLINQ fashion:

private void GetTransactionDetails(string _trID);

_sortedList.AsParallel().WithDegreeOfParallelism(10).Select(x => GetTransactionDetails(x.TransactionID)).ToList();

为避免阻塞UI线程，可以将其包装在单个Task.Run中:

To avoid blocking the UI thread, you can wrap this in a single Task.Run:

await Task.Run(() => _sortedList.AsParallel().WithDegreeOfParallelism(10).Select(x => GetTransactionDetails(x.TransactionID)).ToList());

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