Visualization loading stuck but is returned immediately after switching sheet back and forth

[Ossi]

Hi

I have an issue where sometimes a visualization gets stuck loading for several minutes without ever returning any results, but is almost immediately returned after e.g. switching to the next sheet and then returning back to the original sheet.

Server resources are only consumed in the very early stages of the sheet/visualization load and according to resource monitor it seems like nothing is happening during the next minutes. It almost feels like Qlik Sense gets everything done, filtered and calculated during the first minute or so but then "forgets" to return any results.

Calculation logic of the visualization is quite complex and it's understandable that it takes some time to complete. It just seems odd that it might never actually return the result during the first try but then works right away after leaving the sheet and coming back.

Any ideas how to solve these kind of "dozing off" issues or what might be causing it?

[rwunderlich]

What type of visualization is this?  Does this happen to multiple visualizations and or multiple apps?

-Rob

[Ossi]

I have basically one app (or copies of it) with about two or three sheets with visualizations with this behavior. The visualizations are basic bar charts, combo charts and line charts with more complex dimensions and measures used than most other visualizations. Sheets contain other visualizations as well.

The bar chart visualization utilizes multilayered "per customer" aggregation functions with similar set analysis constraints to achieve dynamic calculations, and the other visualizations are more of cumulative costs type of visualization that check if row's date range (Start date and End date) hits the running numbers in X axis (completely separate dimension).

They all work as intended but area somewhat unreliable if they will be loaded or not. I'm aware that these visualizations are combining very resource heavy functions (that might even go against best practices) but it seems to be the only way to do these types of dynamic calculations required. Calculations taking some time and being slow is not so much of an issue but them being unreliable if they return the result or not is, as it often seems that Qlik is done doing anything on the server any more (according to CPU, memory, disk read/write and network usage) but also the result is not returned.

Is there any way to try to refresh visualizations on Qlik sheet without reloading the whole page and losing selections? Even with an extension or something similar?

[Ossi]

I continued testing this with a colleague and by myself:

- I was able to reproduce multiple times a behavior where when opening the sheet for the first time, the sheet got stuck loading several visualizations until I hit refresh, after which the sheet and all of its visualizations got loaded in maybe two seconds (indicating that everything was ready in the background but the result just wasn't returned for some reason).

- We tested with a colleague two versions of the app: one with time range filtering handled via set analysis conditions in measures (1), and another one with time range filtering handled via "AsOfCalendar" type selection (2). They returned somewhat differing results:

(1) When the first version (with set analysis condition) got stuck, also my colleagues session got stuck in a completely different sheet. It was released immediately and only after I either hit refresh, went to the next sheet, or closed my app. If I went to the next sheet and then came back, I was able to load the sheet and its visualizations in a couple of seconds.

(2) When the second version (with "AsOfCalendar" type selection) got stuck, I wasn't able to go the next sheet and come back as it was so stuck that only refreshing or quitting the app released the app (so it was kind of still thinking about the previous sheet even after switching to the next one). Also, it similarly stuck my colleagues session in a different sheet and he couldn't load sheets until I refreshed my session or quit the app.

After these tests it seems more and more likely that the Qlik engine has already finished handling the data and calculations but just doesn't realize that it should return results. In addition it seems to cause trouble in other user sessions so that they can't load data/visualizations until the issue in another session gets solved.

[rwunderlich]

I recommend you open a case with Qlik Support on this issue.

-Rob