Not OP, but that hasn't come up for me very often. If a command output is really long or takes a long time to run I'll normally run it using M-& (async-shell-command) instead of running it in a shell buffer.
Long lines are a more general issue with Emacs, but there's changes in Emacs 27 that should mostly solve it.
The fact that it can happen and does happen leads me to avoid Emacs' shell modes altogether. I just don't want my Emacs freezing on me ever. Considering how much I do in it, it freezing on me is an utter and complete disaster that I want to completely avoid even if it doesn't happen often.
"there's changes in Emacs 27 that should mostly solve it"
If you're talking about the solong mode integration, that's just a hack that kind of works for static buffers, but won't help in dynamic buffers like shell-mode.
To really and truly fix this issue, a core part of Emacs will have to be rewritten, and since that part is written in C and is pretty hairy, no one seems to want to deal with it. So it probably won't happen any time soon.
I'm just hoping Emacs' libvterm integration provides a good workaround, at least for using a shell from within Emacs. I'll have to give it a try one of these days.
Emacs would freeze on me when this happens.
Is there a way around this apart from running a shell under libvterm? Or is this even still an issue under libvterm too?