Azure Function EventHub Trigger receiving request but some requests don't trigger the function

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Azure Function EventHub Trigger receiving request but some requests don't trigger the function

Haoran Zhang 21

My Azure function is receiving messages from EventHub as I can see in App Insights from the request count. However, not all requests are triggering the function. One weird thing though, while I am running my tasks synchronously, each request is fulfilled. When I run the tasks in the async method and use await Task.WhenAll(), some requests are not fulfilled. When I check the App Insights through operation id or invocation id, I can only find 1 request records. Any idea about the issue?

Bruno Lucas 4,436 Reputation points MVP

2022-06-03T01:02:10.843+00:00

Could you share the code...or part of it?

Haoran Zhang 21

[Function("function1")]
public static void Run([EventHubTrigger("eventhub", Connection = "connectionstring", ConsumerGroup = "consumergroup")] string[] input, FunctionContext context)
{
var logger = context.GetLogger("trigger");
logger.LogInformation("Get {0} requests {1}", input.Length.ToString(), context.InvocationId);

        List<Task<double>> taskList = new List<Task<double>>();
        Task<double>[] taskArray = new Task<double>[queryList.Count];
        int index = 0;

        foreach (Query query in queryList)
        {
            logger.LogInformation("Request {0}: start execution", query._requestId);
            taskArray[index] = ExecuteRequest(logger, query);
            index++;
        }
        CancellationTokenSource source = new CancellationTokenSource();
        CancellationToken token = source.Token;

        try
        {
            Task.WaitAll(taskArray, 20000, token);
        }
        catch (OperationCanceledException e)
        {
            logger.LogInformation("Query Cancellation Exception{0}", e.Message);
        }
        catch (AggregateException e)
        {
            for (int i = 0; i < e.InnerExceptions.Count; i++)
            {
                logger.LogInformation("Query Exception{0}", e.InnerExceptions[i].ToString());
            }
        }
    }

Haoran Zhang 21 Reputation points

2022-06-03T04:40:50.2+00:00
public static async Task<double> ExecuteRequest(ILogger logger, Query query)
{
logger.LogInformation("Request {0}: executing", query._requestId);
var queryTimer = new Stopwatch();
queryTimer.Start();

Result results = await reader.GetDataAsync(query); logger.LogInformation("Request {0}: Finish execution", query._requestId); queryTimer.Stop(); TimeSpan timeTaken = queryTimer.Elapsed; return timeTaken.TotalSeconds; }

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Bruno Lucas 4,436 Reputation points MVP

2022-06-03T01:02:10.843+00:00

Could you share the code...or part of it?
Haoran Zhang 21 Reputation points

2022-06-03T04:40:35.547+00:00

[Function("function1")]
public static void Run([EventHubTrigger("eventhub", Connection = "connectionstring", ConsumerGroup = "consumergroup")] string[] input, FunctionContext context)
{
var logger = context.GetLogger("trigger");
logger.LogInformation("Get {0} requests {1}", input.Length.ToString(), context.InvocationId);

List<Task<double>> taskList = new List<Task<double>>(); Task<double>[] taskArray = new Task<double>[queryList.Count]; int index = 0; foreach (Query query in queryList) { logger.LogInformation("Request {0}: start execution", query._requestId); taskArray[index] = ExecuteRequest(logger, query); index++; } CancellationTokenSource source = new CancellationTokenSource(); CancellationToken token = source.Token; try { Task.WaitAll(taskArray, 20000, token); } catch (OperationCanceledException e) { logger.LogInformation("Query Cancellation Exception{0}", e.Message); } catch (AggregateException e) { for (int i = 0; i < e.InnerExceptions.Count; i++) { logger.LogInformation("Query Exception{0}", e.InnerExceptions[i].ToString()); } } }
Haoran Zhang 21 Reputation points

2022-06-03T04:40:50.2+00:00

public static async Task<double> ExecuteRequest(ILogger logger, Query query)
{
logger.LogInformation("Request {0}: executing", query._requestId);
var queryTimer = new Stopwatch();
queryTimer.Start();

Result results = await reader.GetDataAsync(query); logger.LogInformation("Request {0}: Finish execution", query._requestId); queryTimer.Stop(); TimeSpan timeTaken = queryTimer.Elapsed; return timeTaken.TotalSeconds; }

Answer 1

Bruno Lucas 4,436 MVP

What version of Azure function are you using? Versions 5+ support now this setting. You could try increase the time and/or add retries and maybe reduce the delay here: Task.WaitAll(taskArray, 20000, token);

Haoran Zhang 21 Reputation points

2022-06-06T16:51:01.067+00:00

Thanks for the help, we found the root cause why the number of requests does not match the logging and it's mostly due to the App Insights limit that it was not able to catch all the logging. After store the logs to storage, we are able to find the correct number of executions.

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Azure Function EventHub Trigger receiving request but some requests don't trigger the function

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