Azure Logic Apps

Question

Hi

I have a scenario in logic apps

we receive lot of order files( one file for one order) and logic all application takes this order files from Azure Blob storage.
for each order file one logic app instance gets instantiated,In the logic app we are calling downstream Rest services.

but these rest services are not designed to handle Lot concurrency, only maximum of 15 concurrent connections it can support.

but logic app instances are getting created on the file arrival, to handle this situation i want to control no of Logic apps they are getting instantiated I need to control. For that i have set the Trigger Concurrency Property to 15, That menace maximum 15 instance of logic app instance gets created.

in this approach if we receive 15 thousand files in the Azure blob storage, only 15 files gets picked up and all the res of the files will be waiting in Azure Blob storage? or all the files gets picked up and only 15 will process and rest all waiting in any internal queue ?

please help me to understand this.

Answer 1

Hello @Amar-Azure-Practice ,
Thank you for reaching out. Yes, the files will be left in the storage account. But there are 5 parameters which we need to emphasize upon.
• “The number of Blobs to return from the trigger”:- The blob storage trigger is based on polling mechanism, and using this setting you can limit the number of files getting polled per interval time. The maximum is 100.
• “Time interval & frequency”:- This setting will define how frequently you will want to fetch the number of files mentioned above.
• “Trigger concurrency” :- Which is already defined by you. This limit describes the highest number of logic app instances that can run at the same time, or in parallel.
• “Maximum waiting runs”:- This limit describes the highest number of logic app instances that can wait to run when your logic app is already running the maximum concurrent instances. The maximum is 100.
• “SplitOn items” - For triggers that return an array, you can specify an expression that uses a 'SplitOn' property. This expression references the array to use for creating and running a workflow instance for each array item.
Now suppose If the “Maximum waiting runs” mentioned above reaches its limit, the recurring triggers start skipping polling attempts as mentioned here, if polling attempt is skipped, the files are not skipped. Additionally you can also refer to this document to handle throttling issues.
Please let me know if there are any additional concerns, I will happy to continue with our discussion.