Principia (with JNSQ) is filling RAM with 500 MB/s of garbage

[Krazy0]

After much troubleshooting stuttering issues, I built a new Principia + JNSQ + MemGraph install and confirmed it's generating an absurd amount of RAM garbage. JNSQ alone (with dependencies) is not doing this. The GC several times a second is causing stuttering. Somehow it doesn't crash. The debugging narrative is here FYI but probably not much more help. https://forum.kerbalspaceprogram.com/topic/229808-stuttering-from-100-mbs-memory-leak/#comment-4501916

KSP.log

Player.log

glog.zip

https://i.imgur.com/OUZJHIv.png

I suspect older versions of Principia are also doing this too based on recollection of stuttering, but I haven't tested.

Update: I tested on an older KSP install with Principia Lame (and about 80 mods including JNSQ) and it also has very similar behavior.
Update 2: Also tested an even older Principia "2022082708" stock system, no JNSQ. Garbage generation at KSC is worse, about 30 MB collected every 3 sec. Tracking station is similar to later versions, about 400 MB/s.
Update 3: an old KSP 1.12.3 modded install without Principia is better in the tracking station; GC is about 8 MB every 10 s. Trivial stuttering.

[pleroy]

I am not sure what you expect us to do with this report. We have plenty of users running JNSQ and Principia and if it was that bad we would have heard about it years ago. So it has to be somehow related to your exact setup, including the 80 unnamed mods and the save. And of course, the logs don't tell us anything useful.

I am a bit confused by your update 2 above. Are you seeing 400 MiB/s with stock KSP, Principia, and no other mod? That sounds very odd. (I would think that the version of Principia would not matter, so please don't go back to a 2022 version, we won't debug it.)

One thing I notice in your logs is that you have about 30 asteroids and comets. On a machine with 6 cores this is not going to be conducive to a great user experience, as explained in the FAQs. I would certainly not expect it to burn RAM, but it won't be fast.

Note that Principia is doing most of its allocations in unmanaged memory (C++) so I am not sure how that interacts with MemGraph. At this point I think you've go to do your homework as suggested by siimav here and use the Unity Profiler to give us precise information about where the memory is consumed.

Finally I'll point out that it's not useful to post a PSA on the forum to the effect that "Principia doesn't work with JNSQ", it doesn't help users and it doesn't help us make progress on the issue.

[siimav]

Had a quick look and it does appear that Principia changes something.
2 profiler captures from TS, only difference is Principia being installed.

[pleroy]

Thanks for looking into this. That's interesting. It may be that the way we do rendering is somehow expensive and that we could improve it (or not, who knows).

I am going to ping @eggrobin because I am not familiar with that code, which has to do with axial tilt. However, since the code has essentially not changed since 2016, I am going to go out on a limb and claim that this has nothing to do with the performance issue experienced by the OP (having 30 asteroids is going to be much, much worse).

[siimav]

Interestingly, on my PC the incremental GC did appear to churn through all that garbage with only minimal frametime inconsistencies. Could very well be that the impact only becomes apparent when a bunch of other mods throw out excessive amounts of allocations as well.

[Krazy0]

Hi all. Sorry @pleroy if my OP was unclear, especially the test sequence. The link to the troubleshooting in the KSP forum was initially on my install with 80 mods but that's not what I'm presenting here (hence not listing them). The OP data here was for a new KSP build with only JNSQ, Principia, MemGraph and their dependencies. The DLLs are listed in the KSP file attached, line 114 Environment Info.

I have been playing with Principia for a couple years with JNSQ (love it!) and the stuttering is only annoying, not game breaking, with a minimal mod list and a new save. It's slowly gotten worse as my save file has grown, but still playable. I'm upgrading my PC and took a new interest in maximizing performance, so I dug deeper. I'm very surprised to see this huge memory usage while the game play is still "not terrible"... like @siimav found above. I'm just hoping you can find some optimization to help people with tons of mods or a slower machine.

I have not tired a build with Principia exclusively. Yes, I should exclude JNSQ as well. JNSQ alone does not have this memory usage issue. I assumed it was JNSQ so I started building with that. I'll rebuild another install with only JNSQ and MemGraph. Actually before that, I'll gather data for unmodded KSP (I have tested that but need data).

Asteroids- good point I forgot to turn them off in the default Kopernicus settings. I did turn them off and delete all but 3 in my main career save and didn't notice a big speed-up, so I don't think that's the smoking gun. But what would happen if someone had 30 ships in orbit? And 50 parts discarded on the surface of Minmus and 250 flags like I do in my main save?

I really don't know exactly how MemGraph is working. I believe it's intended to track the unmanaged memory and see issues like this. My knowledge is reaching its limit. I'm a hardware EE just learning more about of heap vs. stack, unmanaged memory, etc. I've used microcontrollers with single thread and local variables. Thanks for help with the profiling @siimav.