Moodle in English: Tests settings for performance and usability

Tests settings for performance and usability

by Stéphane Poinsart - Tuesday, April 14, 2020, 8:40 PM

Hello,

I'm setting up some tests for courses with a large amount of students (100 to 300).

And, it will not sound like a big surprise, but we need to do many more online tests, and bigger tests this year than any other year before.

I'm worried about the loads for some test settings... In particular with the first 2 "When time expires" auto-submit settings. And the alternative where the student get 0 if he does not submit it before the countdown does not sound like a pleasant user experience either.

If i give a test to 300 students, and 200 of them do not finish in time, does that mean that the server will get the auto-submit load for 200 http requests exactly at the same second ? I'm planing to give to give a max duration a few minutes larger than the begin / end date duration, to spread the test usage a bit, but i still think a large part may auto-submit it at the same time at the end.

Do you have any suggestion on how to best tweak the test settings to handle the load ? Or experience about how big of a problem it could be ?

Should i recommend splitting big tests in smaller ones ? (performance is not the only thing that we would take in consideration for this decision).

Is there a "please wait" screen client side in moodle code that delay the submission of large quiz to avoid killing the servers in those conditions ?

We are using this setup :

Moodle code / webserver : 4 core, 8Gb ram, 500Gb SSD, Debian 10
Database : 2 CPU, 4Gb ram, 40Gb ssd, postgresql 9.6
Moodle benchmark plugin give it the score 101, with no warnings.

Thanks for the help,

Stephane

Re: Tests settings for performance and usability

by Visvanath Ratnaweera - Tuesday, April 14, 2020, 10:38 PM

With some imaginative user-side "tweaks" you can relieve the load on the server infrastructure. You are going to need them, the servers seem to br modest to me. (Are the dedicated hardware or virtual machines? Can't you add more RAM to the database server?)

Instead of one wave of 300 candidates, if could break them in to 6 waves of 50 each, with 5 min intervals, that'll make a huge difference.
Instead of clock time, set the duration of the exam and tell your candidates that their time is measured individually. (Give them trial exams to gain trust.)
Set long but easy to remember passwords for the exam. The different typing speeds, typos will spread the candidates.
There is a big difference between 20 questions on one page and only 5 questions on one page, specially the first page, which is the hard fought one.
This one I am not so sure, but worth comparing: Instead of auto-submit make the exam manual submit and give the students a long, 5 min., tolerance, but keep the right to subtract points for delay.

Before all that happens, have trial exams for smaller batches and monitor the server closely. The usual tool in this forum is Munin.

I understood that you are not looking for technical performance improvements. If so, they are well documented in the forum documentation https://docs.moodle.org/en/Performance and https://docs.moodle.org/en/Performance_FAQ.

P.S. The Moodle benchmark plug-in doesn't say anything about the scalability. It'll show you whether there are poor components or a malconfiguration.

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Re: Tests settings for performance and usability

by Stéphane Poinsart - Tuesday, April 21, 2020, 12:34 AM

Hello Visvanath,

Thanks a lot for your very useful response. We will monitor the performance on smaller tests and implement your suggestions as necessary. We try to be cautious but not overburden the student and teachers with things like long passwords if they serve no other purpose but I like having the options you suggest if things goes wrong for the biggest exams.

Our IT department also added a lot more power to the virtual machines and adjusted webserver / database configuration to handle the appropriate simultaneous query count.

Best regards,

Stephane

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Tests settings for performance and usability