Azure Functions
An Azure service that provides an event-driven serverless compute platform.
5,619 questions
Azure Function Azure Service Bus Trigger Delay Issues
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Artyom Gilevich
20
Reputation points
An Azure Functions app using a Consumption plan has been experiencing significant delays, sometimes taking hours for messages to be handled after being enqueued. The Functions app was not running during these delays, and Application Insights logs have been reviewed without finding the issue (there were literally no logs between the enqueue time and the processing start time, which took a few hours this morning). Additionally, the visibility settings on the messages confirm they are visible immediately upon being pushed to the queue.
The Function App is implemented using .NET 9 isolated worker model.
The most interesting detail here is that the Function app starts processing my messages as soon as I open the Function App in the Azure Portal after a few hours of delay.
What are the options for debugging this issue?
{count} votes
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Florian Lenz 0 Reputation points MVPApr 1, 2025, 12:21 PM What language/framework do you use?
Do you use node.js?
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Artyom Gilevich 20 Reputation points
Apr 1, 2025, 12:23 PM @Florian Lenz I'm using .NET 9 isolated worker model.
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Florian Lenz 0 Reputation points MVP
Apr 1, 2025, 2:04 PM ok, with node.js I would have had a guess. With .NET is new to me.
Just some more questions:
- Have you implemented any custom dependency injection or startup configuration that might affect host startup or trigger registration? Or just a basic functionallity?
As a quick fix:
You can try to use a "flex consumption plan" and use an always on instance.
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Ranashekar Guda 1,140 Reputation points Microsoft External StaffApr 2, 2025, 3:26 PM Hello @Artyom Gilevich,
Just checking in to see if the below answer provided by @Florian Lenz helped. -
Ranashekar Guda 1,140 Reputation points Microsoft External Staff
Apr 3, 2025, 3:23 PM Hi @Artyom Gilevich,
We haven’t heard from you on the last response and was just checking back to see if you have a resolution yet.
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