Powershell Azure function times out on processing queue - powershell

Question

I have Azure function written in powershell and processing seems to be stopping for no apparent reason with timeout. Message never gets even to start being processed. This does not seem to be code related since code never even have a change to start since the first line of code is Write-Host "PowerShell queue trigger function processed work item: $QueueItem" which does not appear in log
Host.json
{
"version": "2.0",
"functionTimeout": "00:04:00",
"managedDependency": {
"enabled": true
},
"extensionBundle": {
"id": "Microsoft.Azure.Functions.ExtensionBundle",
"version": "[1.*, 2.0.0)"
},
"extensions": {
"queues": {
"maxPollingInterval": "00:00:02",
"visibilityTimeout": "00:00:30",
"batchSize": 16,
"maxDequeueCount": 2,
"newBatchThreshold": 8
}
}
}
Function.json
{
"bindings": [
{
"name": "QueueItem",
"type": "queueTrigger",
"direction": "in",
"queueName": "metadataservicequeue",
"connection": "useastbootdiag_STORAGE"
}
]
}
Script
# Input bindings are passed in via param block.
param([string] $QueueItem, $TriggerMetadata)
# Write out the queue message and insertion time to the information log.
Write-Host "PowerShell queue trigger function processed work item: $QueueItem"
Write-Host "Queue item insertion time: $($TriggerMetadata.InsertionTime)"
Write-Host "Starting executing Invoke-AzureRMCommand with parameters $($TriggerMetadata["VMName"]), $($TriggerMetadata["ResourceGroup"])"
$return = Invoke-AzureCommand -vmName $TriggerMetadata["VMName"] -resourceGroup $TriggerMetadata["ResourceGroup"]
Write-Host "Finished executing Invoke-AzureRMCommand with parameters $($TriggerMetadata["VMName"]), $($TriggerMetadata["ResourceGroup"])"
$json = #"
[
{
"Return" : $($return | convertto-json),
"VMName" : "$($TriggerMetadata["VMName"])",
"ResourceGroup" : "$($TriggerMetadata["ResourceGroup"])"
}
]
"#
Write-Host "Outputing following to Log Analytics $json"
Post-LogAnalyticsData -customerId $env:CustomerID -sharedKey $env:SharedKey -body ([System.Text.Encoding]::UTF8.GetBytes($json)) -logType "MetaDataLog"

Answer 1

Powershell Azure Functions by default are not scaling well on consumption plan and poorely scale on dedicated plan due to default settings. If you function is not CPU bound and expected to scale well due to high number of queue items. You'd need to modify FUNCTIONS_WORKER_PROCESS_COUNT (https://learn.microsoft.com/en-us/azure/azure-functions/functions-app-settings) to higher number then default 1 and increase value of PSWorkerInProcConcurrencyUpperBound (https://learn.microsoft.com/en-us/azure/azure-functions/functions-reference-powershell#concurrency) to higher number of default 1