High client CPU usage when accessing course outline in Studio

[tech_mil]

NOTE: Update in later posts - issue seems to be client side after investigation

Hello,

We are running tutor v19.0.2 and EDX Sumac

We are having an issue with one particular course in studio. It takes a while to load any of the pages, and can take up to 3 minutes to load a unit to edit. Once in the subsection the other units load fast.

We have other courses on the same platform and they seem to load fine, and there are no issues in the logs that do not exist in other courses. It just seems to sit and then all of a sudden spit out the page and all the logs. Does anyone have any tips on how I could debug this? I get the feeling that something is waiting on a process to complete, and it times out, as it seems to fairly consistent around the 3minute mark. I should also note there is no high cpu or disk IO usage.

When viewing the course as a learner there is no notticeable speed issues.

Thanks in advance!

[tech_mil]

The only error I see (which is not unique to this course) is the following:

ERROR 16 [cms.lib.xblock.upstream_sync] [user 4] [ip 1.2.3.4] upstream_sync.py:125 - Tried to inspect an unsupported, broken, or missing downstream->upstream link: ‘block-v1:org+course+term+type@html+block@63a0740cf53a45a9bdc53378c03a2e28’->‘None’

So I am not sure if this is part of it.

[tech_mil]

I upgraded to Tutor 19.0.5 after seeing this forum post Performance Issue in Studio with Large Courses – Multiple Clipboard API Calls Causing Browser Crash - #2 by dave however this did not fix my issue.

I have been exploring this further - it would appear it is a client side issue. I get high (20%) usage when opening the course outline in studio. If I watch the CPU usage in task manager it stays like this for a while, before dropping to basically 0% for the tab that has studio running.

I wonder - is studio getting all content from the course and processing it in the background when opening the course outline, is this intended behaviour?

[tech_mil]

Sorry, turns out I had to run tutor images build mfe to update the authoring MFE on top of upgrading to openedx sumac.3 as mentioned in the previous comment!