Hello,
this question is about the STACK plugin which seems to be well suited for developing math questions.
I asked the moodle admin in my university to install the STACK plugin to test it (actually, he will). He told me that people who inquired about STACK told him that STACK uses a lot of resources.
What is the reality? Is STACK very demanding in terms of resources compared to, for example, the Formulas plugin that I use intensively?
Thanks for infos.
Daniel.
I think this is something to be aware of, but not something to be unduly frightened of.
Because of what STACK is doing (which is very worthwhile if you are a mathematician) it certainly is more heavy-weight than other quesiton types. A sensible way to start is to use it for classwork first, not final assessment. Then, once you can see what impact it has on your servers, you can move on to higher-stakes use.
Also, the part of STACK which is most demanding is the back-end code which processes the maths using some software called Maxima. The good way to set things up puts that load onto a separate server, using https://github.com/maths/stack_util_maximapool, or these days, more conveniently, https://github.com/uni-halle/maximapool-docker. Doing that deals with most concerns about performance. Also, worth ensuring that you are on Moodle 3.9 or later, since MDL-67183 helps. Again, you may not need to do that when initially trying STACK out to see if it is something you want, but it is a useful option as your use grows.
We use MaximaPool on some pretty modest servers (we have two of them, but only because we always have multiple servers for resiliance), and they never get about 10% CPU load (the average is nearer 2%). And, that includes on the busiest day this year, when students attempted 18,000 questions in one day.
Very strict data protection laws and the extra effort coming with ensuring compliance.
Setting up your own open source system on premises is much easier in most cases.
@Tim Hunt:
I forwarded your suggestion to the responsible person in Göttingen.
Hello,
my name is Stefan Koospal, System Admin, Math. Institut Goettingen. My team created that "go" solution for the STACK back end. The solution is in production.
Further on we offer a Kubernetes based service with this solution(Public Maxima Pool). It's free to use without notice. This service should help to spread the use of STACK. It used by STACK users in Europe.
Online exams with up to 500 users at a time are running smoothless (about 100 requests per minute). At the moment we see the limit at 1000 STACK(=maxima) requests per minute. We are just adding 6 blades to be started on request to expand the maximum limit to 2000 requests per minute.
Further details (how to use our Kubernetes cluster, how to use the "go" solution) you can find here:
https://projects.gwdg.de/projects/netzwerk-mathe-digital/wiki/stack-maxima-pool-technical-details
