Exam AZ-204 topic 5 question 9 discussion

A is the correct answer

The error shown is a SQL Server error not an Azure functions error. https://forums.asp.net/t/2004198.aspx?Timeout+expired+The+timeout+period+elapsed+prior+to+obtaining+a+connection+from+the+pool+This+may+have+occurred+because+all+pooled+connections+were+in+use+and+max+pool+size+was+reached+ The actual issue appears to be that you have too many simultaneous functions running, the solution is to limit the batch size (# functions that can run in parallel) https://social.msdn.microsoft.com/Forums/azure/en-US/a2955297-1c14-45f2-b799-6346b340519a/how-does-batchsize-works-in-hostjson?forum=AzureFunctions

A. In the host.json file, decrease the value of the batchSize option

The answer should be A. The error message shows that there is not enough connections, which means that the concurrency is too high. Too many instances are running parallel. So we have to reduce the concurrency of the app. https://github.com/Azure/azure-functions-host/wiki/host.json If you search for "batchSize" on the above official microsoft github wiki page for host.json, you will find the explanation for the batchSize: // The number of queue messages to retrieve and process in // parallel (per job function). The default is 16 and the maximum is 32. "batchSize": 16,

Explanation: With the Premium plan the max outbound connections per instance is unbounded compared to the 600 active (1200 total) in a Consumption plan. Note: The number of available connections is limited partly because a function app runs in a sandbox environment. One of the restrictions that the sandbox imposes on your code is a limit on the number of outbound connections, which is currently 600 active (1,200 total) connections per instance. When you reach this limit, the functions runtime writes the following message to the logs: Host thresholds exceeded: Connections.

got this question on 29/06/2023

Answer A, the error is at SQL Instance no a function error, and the questions does not say the plan you have... so you cannot asume that you are using consumtion plan.

None of the options provided are correct I think

the most appropriate solution in this case is to optimize the function code and increase the Max Pool Size property of the connection string used by the function.

A is the correct answer

A is the correct answer

This is a question for a machine. I have to remember all options in host.json. How many of these random questions can be asked by Microsoft. https://docs.microsoft.com/en-us/azure/service-bus-messaging/service-bus-messages-payloads https://docs.microsoft.com/en-us/azure/service-bus-messaging/service-bus-messages-payloads https://docs.microsoft.com/en-us/azure/service-bus-messaging/service-bus-messages-payloads https://docs.microsoft.com/en-us/azure/service-bus-messaging/service-bus-messages-payloads https://docs.microsoft.com/en-us/azure/service-bus-messaging/service-bus-messages-payloads https://learn.microsoft.com/en-us/azure/azure-functions/functions-host-json#aggregator According to the above link batchSize is about application insights. Another marvel from Microsoft to make it without application insights anywhere and cherry on top to ask that mistake in an exam. Especially when batching will make people think it has something to do with batching the calls. Microsoft wins again https://learn.microsoft.com/en-us/azure/azure-functions/functions-host-json#aggregator

it can not be C when Pool connection is running out, it's able the DB connections pool is out, changing the function plan only allow more callers to access the DB but it does not increase the connections pool size, so it will still be out of connections in DB.

It's the DB connection Pool..... you scale up the app also no use.. the connectors from DB Pool not release fast enough for the next app to operate.

A is the correct answer

Got it on 03/2022, I chose A. In the host.json file, decrease the value of the batchSize option

A: seems not correct for me. see: https://docs.microsoft.com/en-us/azure/azure-functions/functions-host-json#aggregator it just seems to affect metrics. Besides an increase would help => more elements per function => less functions => less connections B: might help (if scaling can be limited), but for itself is not a solution C: does not help since source of problem (to many incoming connections to SQL Server) unchanged. There is no problem with number of outgoing connections in function D: searching for "queueScaling" only resulted in AZ-204 question results ;-) So what should I choose? While doing research for point B I git to this site https://medium.com/microsoftazure/azure-functions-limiting-throughput-and-scalability-of-a-serverless-app-5b1c381491e3 I found the hint that a premium plan can limit instances, which is verified here: https://docs.microsoft.com/en-us/azure/azure-functions/functions-premium-plan?tabs=portal#maximum-function-app-instances So I would go with C but for the option to limit scaling and not for the explanation in the result.