Solved: Re: No Data Returned: Server Response Concurrency...

BraneyBI · ‎12-08-2017

My Power App connects SQL on Azure VM. This morning, my App is not returning any data and is throwing an error : "Server Response: Concurrency Limit Exceeded"

Strange thing is, I am the ONLY person working on the App at the moment. How can I fix this error?

I have removed the tables and reconnected to them, but that did not fix the issue.

BraneyBI · ‎12-11-2017

Actually, we determined that my app had too many concurrent calls to the same datasource on the same screen of the app.

Per the Product team:

Concurrency limit occurs when you have a lot of parallel calls on a screen to your data source. I believe the limit is 6 calls.

Having never seen this issue documented before, I now know the if you have a need to hit the same source (SQL table in my case) more than 6 times on a screen, you should first place the relevant rows in a collection, then hit the collection within the app.

Summary:

In the OnStart (or OnVisible) property of the screen, place:
ClearCollect(MyCollection, [schema].[MyTable]),

Then just call to your collection as needed on the screen.

View solution in original post

v-micsh-msft · ‎12-10-2017

Hi @BraneyBI,

Are you using Azure SQL DataBase here? I think your issue here should be mostly related with the limits in Azure (SQL Database) connection.

For Azure SQL DataBase, there are session and worker (requests) limits.

"

The maximum number of concurrent sessions and workers are determined by the service tier and performance level (DTUs and eDTUs). New requests are rejected when session or worker limits are reached, and clients receive an error message. While the number of connections available can be controlled by the application, the number of concurrent workers is often harder to estimate and control. This is especially true during peak load periods when database resource limits are reached and workers pile up due to longer running queries.

"

For more information about the limits, please check:

Azure SQL Database resource limits

Regards,

Michael

Community Support Team _ Michael Shao
If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.

BraneyBI · ‎12-11-2017

Actually, we determined that my app had too many concurrent calls to the same datasource on the same screen of the app.

Per the Product team:

Concurrency limit occurs when you have a lot of parallel calls on a screen to your data source. I believe the limit is 6 calls.

Having never seen this issue documented before, I now know the if you have a need to hit the same source (SQL table in my case) more than 6 times on a screen, you should first place the relevant rows in a collection, then hit the collection within the app.

Summary:

In the OnStart (or OnVisible) property of the screen, place:
ClearCollect(MyCollection, [schema].[MyTable]),

Then just call to your collection as needed on the screen.

v-micsh-msft · ‎12-11-2017

Hi @BraneyBI,

Thanks for the clarification and updates.

Regards,

Michael

Community Support Team _ Michael Shao
If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.

PowerAppJammer · ‎12-19-2017

We just ran into this issue this morning. We are loading several collections on visible for the first time only and now see the same error. We haven't changed the app logic for a few days but this error is new to us.

I don't know if there is a way to reduce the number of tables we read in initially, as this was already done to reduce the number of calls while navigating the app.

Any suggestions or was this a recent change/limitation?

Ryan

Anonymous · ‎12-25-2017

Hi @ v-micsh-msft,

our customers are using applications powered by PowerApps. these applications enable nearly 100 staff working in the field to communicate important information on the field to the center. I am afraid to develop applications with this application now that I do not need to summarize the possible situations and notify the user before a significant change is made in order to lose the confidence in the product on the live market. I ask you to clarify the problem and its solution clearly. It's like looking for a comment in a single community, looking for a needle in a haystack.

are there any environments that you write when you make these systematic improvements?

thank you.

wyotim · ‎08-27-2018

@BraneyBIWhile this is an older thread, I just wanted to comment that it helped me out today. I am working on updating an older app and one of the updates is including a Concurrent function for data loading. There are 15 different tables being loaded via the LoadData function and while it worked fine on my iOS device, it would hang when trying to load on my Windows 10 computer. After finding this thread, I broke up the initial statement into three different Concurrent functions and that worked like a charm. Thanks!

Anonymous · ‎11-08-2019

Hey i am trying to patch gallery all items but i am getting an error (Please see the attached Screenshot). I have tried it and it is working with less items in the gallery but when it comes to huge number of items in the gallery it is showing the error.

Please help me out of it.