Styjun

I have a function:

 public async static Task Run([QueueTrigger("efs-api-call-last-datetime", Connection = "StorageConnectionString")]DateTime queueItem,
 [Queue("efs-api-call-last-datetime", Connection = "StorageConnectionString")]CloudQueue inputQueue,
 TraceWriter log)
 {

Then I have long process for processing message from queue. Problem is the message will be readded to queue after 30 seconds, while I process this message. I don't need to add this message and process it twice.
I would like to have code like:

 try
 
 // long operation
 
 catch(Exception ex)
 
 // something wrong. Readd this message in 1 minute
 await inputQueue.AddMessageAsync(new CloudQueueMessage(
 JsonConvert.SerializeObject(queueItem)),
 timeToLive: null,
 initialVisibilityDelay: TimeSpan.FromMinutes(1),
 options: null,
 operationContext: null
 );
 

and prevent to readd it automatically. Any way to do it?

There are couple of things here.

1) When there are multiple queue messages waiting, the queue trigger retrieves a batch of messages and invokes function instances concurrently to process them. By default, the batch size is 16. But this is configurable in Host.json. You can set the batch size to 1 if you want to minimize the parallel execution. Microsoft document explains this.

2) As it is long running process so it seems your messages are not complete and the function might timeout and message are visible again. You should try to break down your function into smaller functions. Then you can use durable function which will chain the work you have to do.

Yes, you can dequeue same message twice.

Reasons:

1.Worker A dequeues Message B and invisibility timeout expires. Message B becomes visible again and Worker C dequeues Message B, invalidating Worker A's pop receipt. Worker A finishes work, goes to delete Message B and error is thrown. This is most common.

2.The lock on the original message that triggers the first Azure Function to execute is likely expiring. This will cause the Queue to assume that processing the message failed, and it will then use that message to trigger the Function to execute again.

3.In certain conditions (very frequent queue polling) you can get the same message twice on a GetMessage. This is a type of race condition that while rare does occur. Worker A and B are polling very quickly and hit the queue simultaneously and both get same message. This used to be much more common (SDK 1.0 time frame) under high polling scenarios, but it has become much more rare now in later storage updates (can't recall seeing this recently).

1 and 3 only happen when you have more than 1 worker.

Workaround:

Install azure-webjobs-sdk 1.0.11015.0 version (visible in the 'Settings' page of the Functions portal). For more details, you could refer to fixing queue visibility renewals