Question

我目前正在使用EventProcessorHost和一个简单的IEventProcessor实现来实现Event Hub阅读器。我已经确认使用Paolo Salvatori的优秀Service Bus Explorer将遥测数据写入事件中心。我已成功配置EventProcessorHost以使用租约和检查点的存储帐户。我可以在存储帐户中看到Event Hub数据文件。我在这一点上看到的问题是IEventProcessor实现似乎没有从事件中心读取任何内容。

我没有收到任何例外。测试控制台应用程序正在连接到存储帐户而没有问题。我注意到我添加到构造函数的日志语句永远不会被调用，因此看起来接收器实际上从未被创建过。我觉得我错过了一些简单的事情。任何人都可以帮我确定我错过了什么？谢谢！

IEventProcessor 实施：

namespace Receiver
{
    internal class SimpleEventProcessor : IEventProcessor
    {
        private Stopwatch _checkPointStopwatch;

        public SimpleEventProcessor()
        {
            Console.WriteLine("SimpleEventProcessor created");
        }

        #region Implementation of IEventProcessor

        public Task OpenAsync(PartitionContext context)
        {
            Console.WriteLine("SimpleEventProcessor initialized.  Partition: '{0}', Offset: '{1}",
                context.Lease.PartitionId, context.Lease.Offset);
            _checkPointStopwatch = new Stopwatch();
            _checkPointStopwatch.Start();
            return Task.FromResult<object>(null);
        }

        public async Task ProcessEventsAsync(PartitionContext context, IEnumerable<EventData> messages)
        {
            foreach (var data in messages.Select(eventData => Encoding.UTF8.GetString(eventData.GetBytes())))
            {
                Console.WriteLine("Message received.  Partition: '{0}', Data: '{1}'", context.Lease.PartitionId,
                    data);
            }

            if (_checkPointStopwatch.Elapsed > TimeSpan.FromSeconds(30))
            {
                await context.CheckpointAsync();
                _checkPointStopwatch.Restart();
            }
        }

        public async Task CloseAsync(PartitionContext context, CloseReason reason)
        {
            Console.WriteLine("Processor shutting down.  Partition '{0}', Reason: {1}", context.Lease.PartitionId,
                reason);

            if (reason == CloseReason.Shutdown)
            {
                await context.CheckpointAsync();
            }
        }

        #endregion
    }
}

测试控制台代码：

namespace EventHubTestConsole
{
internal class Program
{
    private static void Main(string[] args)
    {
        AsyncPump.Run((Func<Task>) MainAsync);
    }

    private static async Task MainAsync()
    {
        const string eventHubConnectionString =
            "Endpoint=<EH endpoint>;SharedAccessKeyName=<key name>;SharedAccessKey=<key>";
        const string eventHubName = "<event hub name>";
        const string storageAccountName = "<storage account name>";
        const string storageAccountKey = "<valid storage key>";
        var storageConnectionString = string.Format("DefaultEndpointsProtocol=https;AccountName={0};AccountKey={1}",
            storageAccountName, storageAccountKey);
        Console.WriteLine("Connecting to storage account with ConnectionString: {0}", storageConnectionString);

        var eventProcessorHostName = Guid.NewGuid().ToString();
        var eventProcessorHost = new EventProcessorHost(
            eventProcessorHostName,
            eventHubName,
            EventHubConsumerGroup.DefaultGroupName,
            eventHubConnectionString,
            storageConnectionString);

        var epo = new EventProcessorOptions
        {
            MaxBatchSize = 100,
            PrefetchCount = 1,
            ReceiveTimeOut = TimeSpan.FromSeconds(20),
            InitialOffsetProvider = (name) => DateTime.Now.AddDays(-7)
        };

        epo.ExceptionReceived += OnExceptionReceived;

        await eventProcessorHost.RegisterEventProcessorAsync<SimpleEventProcessor>(epo);

        Console.WriteLine("Receiving.  Please enter to stop worker.");
        Console.ReadLine();
    }

    public static void OnExceptionReceived(object sender, ExceptionReceivedEventArgs args)
    {
        Console.WriteLine("Event Hub exception received: {0}", args.Exception.Message);
    }
}

Answer 1

问题在于 EventProcessorOptions.PrefetchCount 的价值。

我稍微更改了您的代码，如此处所示（删除 AsyncPump 并干净地关闭接收器）。我发现如果 PrefetchCount 小于10， RegisterEventProcessorAsync 会抛出异常。

namespace EventHubTestConsole
{
  internal class Program
  {
    private static void Main(string[] args)
    {
       const string eventHubConnectionString =
        "Endpoint=<EH endpoint>;SharedAccessKeyName=<key name>;SharedAccessKey=<key>";
       const string eventHubName = "<event hub name>";
       const string storageAccountName = "<storage account name>";
       const string storageAccountKey = "<valid storage key>";
       var storageConnectionString = string.Format("DefaultEndpointsProtocol=https;AccountName={0};AccountKey={1}",
        storageAccountName, storageAccountKey);
       Console.WriteLine("Connecting to storage account with ConnectionString: {0}", storageConnectionString);

       var eventProcessorHostName = Guid.NewGuid().ToString();
       var eventProcessorHost = new EventProcessorHost(
         eventProcessorHostName,
         eventHubName,
         EventHubConsumerGroup.DefaultGroupName,
         eventHubConnectionString,
         storageConnectionString);

       var epo = new EventProcessorOptions
         {
           MaxBatchSize = 100,
           PrefetchCount = 10,
           ReceiveTimeOut = TimeSpan.FromSeconds(20),
           InitialOffsetProvider = (name) => DateTime.Now.AddDays(-7)
         };

       epo.ExceptionReceived += OnExceptionReceived;

       eventProcessorHost.RegisterEventProcessorAsync<SimpleEventProcessor>(epo).Wait();

       Console.WriteLine("Receiving.  Please enter to stop worker.");
       Console.ReadLine();
       eventProcessorHost.UnregisterEventProcessorAsync().Wait();
    }


    public static void OnExceptionReceived(object sender,     ExceptionReceivedEventArgs args)
    {
      Console.WriteLine("Event Hub exception received: {0}", args.Exception.Message);
    }
  }
}

IEventProcessor不从事件中心读取

1 个答案: