Yeah, I've found the Elixir debugger to be pretty useless when debugging multiple processes. I make have use of logging in such cases, and the language abstractions are usually easy enough to understand that I don't really miss a debugger. A huge benefit is that because I'm usually working w/ data structures that don't obfuscate the state within objects/processes, I can look at data the data and just figure out what's going on. The primary reason I want a debugger in Ruby is because some mysterious object from who-knows-where is hiding all the state & I'm just trying to figure out where the heck it came from, let alone what's actually in there.
I just remembered the Tracepoint feature though (it's been a while since I was working in C++ with visual studio). Even when you can't pause execution to debug it's still better to add your tracing in the debugger rather than having to make code changes.
I was always doing stuff on windows/macOS/iOS/Android client libraries so I was always jealous of linux systems programmers who get to leverage Mozilla's rr tool. That's the coolest debugging tool I've ever seen.
Sadly rr cannot work on software that makes any kind of call to GPUs, so its usefulness is pretty limited on a lot of larger software. But when it's usable, imo it's amazing.
If the UI is not GPU accelerated while you are recording, rr will work fine. You can even have GPU calls in the code while recording, they just can't be on code paths that are taken. So a simple command line flag that makes the code choose to use CPU rendering instead of GPU rendering should be fine.
That said, GPU rendering is one of the things that deterministic replay could be most useful for, so it's unfortunate that this doesn't work in rr for now.