Just having Galacticraft and Advanced Rocketry installed is probably enough to do it. I cannot post the entire log as it is literally 22 gigabytes, but this is how it ends: https://gist.github.com/maladaptly/9fd95dcb6beeddc1e41991614ee1f9ca

This was 10,000 chunks per dimension.

Looks like it might be journeymap
[journeymap]: Unexpected error in ChunkRenderController: java.lang.OutOfMemoryError: GC overhead limit exceeded
Were you able to reproduce with JER, Galacticraft and Advanced Rocketry only?

That's only the point at which the runtime finally ran out of memory and had to throw on an allocation. While I can't rule out the possibility that it's leaking memory, that message in itself (or anything in the log, for that matter) doesn't implicate JM at all.

I'll set up another instance with only JER+GC+AR+dependencies but reduce the memory pool size (was 6GB, let's try 3GB) and see what happens.

Reproduced with only JER+GC+AR+dependencies. It got through ~120 dimensions before crashing, so it's not simply a matter of too small a memory pool -- something's either leaking or using memory inefficiently.

Log is once again huge, a whopping 18GB. Here's the tail end:

https://gist.github.com/maladaptly/8aefa783cbc4eac763c5a8dd0e6f8d4d

Tbh it kinda makes sense after 120 dim, never really anticipated that. Gonna need to have a long thought about this.

Gonna close this one as it was never written for very large scans and needs to be rewritten for newer version anyway