How can I speed up my rate of sending event to AzureEventHub?

Question

I am using this simple foreach loop to send events to an Azure EventHub, problem is it seems failry slow and only sends 1-2 events / second, so I feel I must be missing something, how can I speed this up? am I sending them async or what am I doing wrong?

 if (!apiInputPutCalendarService.TimeSlotIdsToClose.Any())
                {
                    return new BadRequestObjectResult(new
                    {
                        Status = "NOK",
                        Error = "There are no timeslots to close",
                        Result = ""
                    });
                }
                else
                {
                    foreach (String calendarTimeSlotId in apiInputPutCalendarService.TimeSlotIdsToClose)
                    {
                        EventHubCDSSoftDeleteTriggerModel scanMsg = new EventHubCDSSoftDeleteTriggerModel
                        {
                            TimeSlotId = calendarTimeSlotId
                        };

                        var scanMessageJsonString = JsonConvert.SerializeObject(scanMsg);

                        await EventHubHelper.SendEventToEventHubAsync(_eventHubClient, scanMessageJsonString);

                        log.LogInformation($"Message: {scanMessageJsonString} sent!");
                    }
                }

its such a small simple message I expected at least 100s of messages to be sent / second

What am I missing here?

Answer 1

Well, have you measured the impact of the logging and the serialization and the call to TimeSlotIdsToClose? Also, I would start by not sending the messages one by one but by sending messages in batches:

await using (var producerClient = new EventHubProducerClient(connectionString, eventHubName))
        {
            // Create a batch of events 
            using EventDataBatch eventBatch = await producerClient.CreateBatchAsync();

            // Add events to the batch. An event is a represented by a collection of bytes and metadata. 
            eventBatch.TryAdd(new EventData(Encoding.UTF8.GetBytes("First event")));
            eventBatch.TryAdd(new EventData(Encoding.UTF8.GetBytes("Second event")));
            eventBatch.TryAdd(new EventData(Encoding.UTF8.GetBytes("Third event")));

            // Use the producer client to send the batch of events to the event hub
            await producerClient.SendAsync(eventBatch);
            Console.WriteLine("A batch of 3 events has been published.");
        }

(source)

Do mind that the code above does not reuse the EventHubProducerClient, which is recommended and that you shouldn't ignore te result of TryAdd as that will tell you whether the message can be added to the batch (there is a size based limit per batch).

Also, since I don't know your code:

Each of the Event Hubs client types is safe to cache and use as a singleton for the lifetime of the application, which is best practice when events are being published or read regularly.

(Source)