Receiving events from event hub was blocked.

Question

In our Cloud Service project, we have 2 instances for work role (deploy to Azure), the work role is consume events from the EventHub using EventProcessorHost(host name is RoleInstance name).
For sending events:
    var
client = EventHubClient.CreateFromConnectionString(serviceBusConnectionString,
hubName);
while (true)
var eventData =
new
EventData(Encoding.UTF8.GetBytes("test"))
{PartitionKey = "key"};
                    eventData.Properties.Add("time",
DateTime.UtcNow);
                client.SendAsync(eventData).Wait();
                Thread.Sleep(50);
Each 50ms, we send one event (event1, 2,3 …….);
For receiving data:    
 public
async
Task ProcessEventsAsync(PartitionContext
context, IEnumerable<EventData>
events)
            //when
we get the event, so we can view the log
Trace.WriteLine(“got events”);
foreach (var
eventData in events)
                // handle the event
Task.Delay(12000).Wait();
await ContextCheckpointAsync(context);
We add the
delay for event operation.
It seems that we cannot receive data in time from the log, seems event6 was blocked for the Event5 delay, after the 12ms, we can receive event6 from the EventHub, and the Event6
delay is 40s(from the log, we send event6 to Hub at 35:10, but we get from Hub at 35:50),
So I wonder to know the maximum number of threads are working on processing fot the EventProcessorHost? Depends on the Partitions?
And is there any way to receiving events in time?

Answer 1

Hi Jordan
Since Task.Delay call blocks the callback, host won't hand over new events until you're done with the current batch. This is due to order guarantee of the events delivered, i.e. host should process the events in order from the same partition.
If event process is taking so long then you should consider to move process job into a separate thread so host can deliver new batch of events while thread is working on the previous batch.