While I am developing the Azure Function App with Event Hub triggered locally, something wired which drew my attention. When I started debugging, my consumer function app will occasionally automatically be triggered with my previous message through event hub, however, I didn't even fire my event hub publisher at that time! It felt like some event messages were stored in some cache places where I have no idea where they are, that were also trying to trigger my function app from background again and again...
My App settings for my function is using UseDevelopmentStorage=true, and is not related to any of my storage account, in addition above scenario did not always happen every time, but it made me concerned because I had no idea why the same message to be triggered multiply times that are out of my control, once message were published and consumed by function app, it should disappear from event hub message queue, right?
Can anyone please let me know where I can check my messaged stored locally or when published in Azure portal? Thank you very much!
Can anyone please let me know where I can check my messaged stored locally or when published in Azure portal?
Firstly,i'm afraid that azure function won't save your messages into cache.Based on the official document:
When all function execution completes (with or without errors), checkpoints are added to the associated storage account. When check-pointing succeeds, all 1,000 messages are never retrieved again.
Above is description of event hub checkpoint mechanism.Besides,you could refer to this blog. The AzureWebJobsStorage is set to be UseDevelopmentStorage=true when you debug function locally,so i suggest you checking the data in the local storage account.When you run it on the portal,associated storage account will be checked.
Here are some similar issues for your reference:
1.https://github.com/Azure/azure-functions-host/issues/2796
2.https://github.com/Azure/Azure-Functions/issues/589
3.https://github.com/Azure/azure-event-hubs-dotnet/issues/358
Of course,you could open a stack here to get more help.