Can you please annotate your graph: when does drop_caches run? Is it every time the yellow line moves back up? When would KStars crash if drop_caches didn't run? At the bottom of the first downward yellow line?
Also, how much swap space do you have? Is that your issue?
PS Off topic, but instead of µSD, you should definitely consider using an SSD with your RPi4.
This is easy to test with the simulator (assuming you have GSC installed so that the simulator generates star images) so you need not wait until nighttime.
I just tried with the simulator (using the latest software) and it worked fine for me.
Here are my settings:
I have done this many times.
On Linux the files should be saved in a directory named something like: ~/.local/share/kstars/autofocus/2022-05-23
When I run unit tests locally, I find I often have to run them in their $BUILD/Tests/$TEST_DIR directory.
So, for instance, in my case that would be:
I'm honestly not sure what the testing environment does when it runs its testing pipeline.
You can see a pipeline output, for instance, by looking at the pipeline link in an MR.
Here's my latest MR: invent.kde.org/education/kstars/-/merge_requests/628
and you can see a pipeline link on that page, which is also here: invent.kde.org/education/kstars/-/pipelines/178754
You should see that my MR passed all the "stable" tests, but had some issues with tests marked "unstable".
Interestingly, I didn't see any reference to TestFitsData in the pipeline output, not sure why.
I just tried to run that test, and also got failures, so it isn't you.
Clearly we need to look at it. Someone must have disabled it.
Don't have time to look right now.
Be aware that we don't have great test coverage, though it has been improved in the past year. It is certainly an area that would be great to improve.
Thank you for looking into things, and looking forward to see what you come up with.
Let me know If anyone who is attending AIC Friday/Saturday is interested in a KStars/Ekos get together. I'd be happy to try to organize an informal "live" group chat. PM me and/or reply to this thread and we can gauge the interest.