Parent - Child Logic Apps

John Dawson 1

I have a Parent Logic App that fires off multiple instances of a Child Logic App, asynchronously; each Child App might take from minutes to hours to run; the Child App runs 10 - 20 instances concurrently; much more and I get throttling errors, which is another issue (I'm not asking about that, now)

Question: how can I get notified when the last Child App has finished? Do I have to poll for it? What's the easiest way to achieve this?

Pramod Valavala 20,591 Reputation points Microsoft Employee

2021-03-01T04:19:37.823+00:00

@John Dawson Just following up here to see if my response help

1 answer

Pramod Valavala 20,591 Reputation points Microsoft Employee

2021-02-26T05:05:57.247+00:00

Since the Child Logic Apps are being run from a Parent (via a For Each Loop I suppose), could just have an action after the for each loop that sends you an email (or other notification service that you require).
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John Dawson 1 Reputation point

2021-03-02T08:52:23.097+00:00

Thanks for the suggestion, but I was hoping there might be some way within the Parent-Child Logic App; my Parent App (currently) uses a "fire and forget" (async) method, so I don't know if any other methods might work i.e. where the Parent App "waits" until all the Children are done?

Pramod Valavala 20,591 Reputation points Microsoft Employee

2021-03-03T05:39:52.267+00:00

@John Dawson Yes. This would all be in the Parent Logic App. The action for nested logic apps will wait until a response and/or all steps are completed.

For calls to child logic apps without a response action, ensure the Asynchronous Pattern setting is set for the action as below

John Dawson 1 Reputation point

2021-03-08T09:13:18.123+00:00

That's the business; does what I need - thanks!

I found it convenient to set the concurrency (say "N") of the Child App to the same value as the concurrency of the loop in the Parent App; if I understand it right, that means the Child App will always run N instances - at least until it's near finishing - and won't have any in a Wait state

Follow up questions:

1) Is it necessary at all to return a status in the Child App i.e. 200?
2) Could I use other statuses to let the Parent App know if an instance of the Child App failed, and therefore decide if I wanted the Parent App to fail also?
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