c# - 在 ActionBlock 中收集结果时阻止收集

Question

我认为在测试方法中，“results”集合变量的类型必须是 BlockingCollection<int>而不是 List<int> .如果我错了，请证明给我看。我从 https://blog.stephencleary.com/2012/11/async-producerconsumer-queue-using.html 中获取了这个示例

private static async Task Produce(BufferBlock<int> queue, IEnumerable<int> values)
{
    foreach (var value in values)
    {
        await queue.SendAsync(value);
    }
}

public async Task ProduceAll(BufferBlock<int> queue)
{
    var producer1 = Produce(queue, Enumerable.Range(0, 10));
    var producer2 = Produce(queue, Enumerable.Range(10, 10));
    var producer3 = Produce(queue, Enumerable.Range(20, 10));
    await Task.WhenAll(producer1, producer2, producer3);
    queue.Complete();
}

[TestMethod]
public async Task ConsumerReceivesCorrectValues()
{
    var results = new List<int>();

    // Define the mesh.
    var queue = new BufferBlock<int>(new DataflowBlockOptions { BoundedCapacity = 5, });

    //var consumerOptions = new ExecutionDataflowBlockOptions { BoundedCapacity = 1, };

    var consumer = new ActionBlock<int>(x => results.Add(x), consumerOptions);
    queue.LinkTo(consumer, new DataflowLinkOptions { PropagateCompletion = true, });

    // Start the producers.
    var producers = ProduceAll(queue);

    // Wait for everything to complete.
    await Task.WhenAll(producers, consumer.Completion);

    // Ensure the consumer got what the producer sent.
    Assert.IsTrue(results.OrderBy(x => x).SequenceEqual(Enumerable.Range(0, 30)));
}

Answer 1

自 ActionBlock<T>默认情况下将其委托(delegate)限制为一次执行一次( MaxDegreeOfParallelism 的 1 )，没有必要使用 BlockingCollection<T>而不是 List<T> .

正如预期的那样，您代码中的测试对我来说顺利通过。

如果ActionBlock<T>通过了一个更高的选项 MaxDegreeOfParallelism , 那么你需要保护 List<T>或者用 BlockingCollection<T> 替换它.