Exam Administrator Gets Logged Out of Admin UI When 200+ Students Are Connected

[ramhee98]

When an Exam Administrator is viewing a Running Exam while approximately 200 students are connected to the SEB server, the Administrator is unexpectedly logged out of the admin UI.

Steps to reproduce the behavior:

1. Go to SEB Server
2. Login
3. Click on Running Exams
4. Click on an Exam
5. Conection is lost

Setup:

• SEB Server Version [2.0.3]
• Debian 11 running docker compose, 12 CPU Cores, 16GB RAM
• Browser [chrome, firefox]
• 200 Students connected to SEB using Moodle 4.4.3+

[anhefti]

Hi Ramon,

We need a bit more information here to be able to track down the problem.
Is the user logged out and redirected to the login page or is the monitoring not showing up and the screen shows the usual turning wheel that indicates page loading?

If the first is true, it possibly has something to do with the user session or token expiry.
If the second one is true there is most probably a performance issue (what I do not expect for about 200 students without screen proctoring) or with network latency.

Do the SEB clients also have trouble to connect to SEB Server in this case?
Are there any errors on the SEB Server logs that might indicate or generate some additional load?
How is the CPU and Memory usage on the SEB Server host at this time?

Thanks and best regards

[ramhee98]

The Exam Supporter is logged out and redirected to the login page.
Whenever an Exam Supporter logs in again after being logged out, he will be again logged out after approximately 5 seconds when viewing a Running Exam.

CPU and Memory usage on the System was about 50%

The currently connected clients were fine. I don't know about new connecting clients.

[anhefti]

Okay, this doesn't sound like a performance issue but more like a user-session issue.
We cannot reproduce this locally yet, and also never faced this issue so far on other setups. But let's try to narrow it down a bit on your system.

Is this only happening for monitoring a particular Exam, or for all Exams?
Might be other SEB Server tabs open within the same browser? Or is the same user already logged in within another browser?
Are there any Errors or Warning or Info Logs on SEB Server logs when it happens that can give use more infos?

We will have a look at the code and try to reproduce it locally meanwhile.

[ramhee98]

This issue affected all Exam Administrators, regardless of which exam they opened.

It occurred whether they had one or two tabs open.
Each Exam Administrator was logged in on only one browser and a single device.

When attempting to export SEB logs, I could only retrieve about five minutes of data. Selecting a longer time span resulted in an empty CSV file.

In just 30 minutes, there were approximately 41,000 log entries, with a few being debug logs like "NetworkRequest: Get current URLSession".

Could the sheer volume of log entries be overwhelming the SEB server?

[anhefti]

Could the sheer volume of log entries be overwhelming the SEB server?

Could be when exporting them or view them in the overall SEB Log page where all logs are sorted unfiltered on DB table fist. But we currently have millions of logs on our setup and this has no impact on monitoring only on SEB Log export for example.

I more suspect that there is one particular SEB session that cannot be rendered for some reason, most probably due to special Unicode character rendering. But this is just an assumption of mine.

What definitely would help are the SEB Server logs here. Either on Monitoring issue or for the export issue, if there is a rendering error, it must be seen in the SEB Server logs.

[ramhee98]

Is any of those Unicode characters a problem?

— \u2014
ü \u00fc
é \u00e9
ô \u00f4
ä \u00e4

[anhefti]

Maybe the first one, but I have tested it locally with all and it seems not to be reproducible:

It also might be a DB data inconsistency for one particular client connection entry. But to track down this issue we best have a look at the SEB Server logs. If an error is available there, it would point us directly to the code where it happens.

If you don't want to add SEB Server logs here, you can send it to me directly via Mail

[ramhee98]

You've got a log file on element.