We have an Azure Function with Service Bus trigger that is triggered on a topic in a service bus topic. We are pushing several hundred thousand per day to the topic. There are several subscriptions to the topic and most of them keep processing the messages but at least one of the subscribers (all are Azure Functions) seems to stop processing the messages intermittently. When the Azure Function is restarted, everything goes back to normal for a day or two.
One function had last run about 18 hours ago and now had 74000 messages in the topic. In the Activity log I cannot see any failures on other indicators as to why it had stopped processing messages.
This is the production Function and in the test environment that "should" be identical but there we are not seeing these issues.
Where should I start looking for the cause of this?
