多次执行Azure功能队列触发器

Question

I have azure function triggered off of a storage queue. The behavior of the function is to create out around 10,000 additional messages to another storage queue for another function (within the same function app) to execute. I'm seeing some strange behavior whenever it executes, where the first function appears to be executed multiple times. I observed this by watching the queue it's publishing to receive significantly more messages than expected.

I understand that the function should be coded defensively (ie expect to be executed multiple times), but this is happening consistently each time the first function executes. I don't think the repeated executions re due to it timing out or failing (according to app insights).

Could it be that when the 10,000 messages get queued up the function is scaling out and that is somehow causing the original message to be executed multiple times?

Answer 1

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. You'll want to look into renewing the message lock while you're sending out 10,000 messages to the next Queue.

Also, since you're sending out 10,000 messages, you may need to redesign that to be more efficient at scaling out what ever massively parallel processing you're attempting to implement. 10,000 is a really high amount of messages to send from a single triggered event.