将 Task.WhenAll 替换为 PLinq

Question

我有一个方法可以并行多次调用 WCF 服务。为了防止目标系统过载，我想使用 PLinq 的能力来限制并行执行的数量。现在我想知道如何以有效的方式重写我的方法。

这是我当前的实现：

private async Task RunFullImport(IProgress<float> progress) {
    var dataEntryCache = new ConcurrentHashSet<int>();
    using var client = new ESBClient(); // WCF

    // Progress counters helpers
    float totalSteps = 1f / companyGroup.Count();
    int currentStep = 0;

    //Iterate over all resources
    await Task.WhenAll(companyGroup.Select(async res => {
        getWorkOrderForResourceDataSetResponse worResp = await client.getWorkOrderForResourceDataSetAsync(
            new getWorkOrderForResourceDataSetRequest(
                "?",
                res.Company,
                res.ResourceNumber,
                res.ResourceType,
                res.CLSName,
                fromDate,
                toDate,
                "D"
            )
        );

        // Iterate over all work orders and add them to the list
        foreach (dsyWorkOrder02TtyWorkOrderResource workOrder in worResp.dsyWorkOrder02) {
            dataEntryCache.Add(workOrder.DataEntryNumber.Value);
        }

        // Update progress
        progress.Report(totalSteps * Interlocked.Increment(ref currentStep) * .1f);
    }));

    // Do some more stuff with the result
}

我已经尝试了一些使用 PLinq 的方法，但我没有找到合适的解决方案。这是我现在的状态。

var p = companyGroup.Select(res => client.getWorkOrderForResourceDataSetAsync(
    new getWorkOrderForResourceDataSetRequest(
        "?",
        res.Company,
        res.ResourceNumber,
        res.ResourceType,
        res.CLSName,
        fromDate,
        toDate,
        "D"
    )
).ContinueWith(worResp => {
    // Iterate over all work orders and add them to the list
    foreach (dsyWorkOrder02TtyWorkOrderResource workOrder in worResp.Result.dsyWorkOrder02) {
        dataEntryCache.Add(workOrder.DataEntryNumber.Value);
    }

    // Update progress
    progress.Report(totalSteps * Interlocked.Increment(ref currentStep) * .1f);
}));

await Task.WhenAll(p.AsParallel().ToArray());

很明显，这不能正常工作。您有什么建议可以使它正常有效地工作，并限制对服务器的最大调用，以便 8 个并行？

Answer 1

PLINQ 仅适用于同步代码。它有一些很好的内置旋钮，用于控制并发并行操作的数量。

要控制并发异步操作的数量，使用SemaphoreSlim:

private async Task RunFullImport(IProgress<float> progress) {
  var dataEntryCache = new ConcurrentHashSet<int>();
  using var client = new ESBClient(); // WCF
  var limiter = new SemaphoreSlim(10); // or however many you want to limit to.

  // Progress counters helpers
  float totalSteps = 1f / companyGroup.Count();
  int currentStep = 0;

  //Iterate over all resources
  await Task.WhenAll(companyGroup.Select(async res => {
    await limiter.WaitAsync();
    try {    
      getWorkOrderForResourceDataSetResponse worResp = ...

      // Iterate over all work orders and add them to the list
      foreach (dsyWorkOrder02TtyWorkOrderResource workOrder in worResp.dsyWorkOrder02) {
        dataEntryCache.Add(workOrder.DataEntryNumber.Value);
      }

      // Update progress
      progress.Report(totalSteps * Interlocked.Increment(ref currentStep) * .1f);
    }
    finally {
      limiter.Release();
    }
  }));

  // Do some more stuff with the result
}

有关详细信息，请参阅 my book 中的秘诀 12.5，其中涵盖了几种不同的节流解决方案。

将 Task.WhenAll 替换为 PLinq

Replace Task.WhenAll with PLinq

c#

parallel-processing

plinq

async-await