It's a key area where I think Go went wrong. Without the ability to kill a goroutine, you can't implement caller-enforced timeouts and canceling — anything that should be able to be canceled has to explicitly check for some signal sent by the controlling party. This is why Go ended up with Context, which infects everything it touched.
And you also can't create Erlang-style supervisor trees; you can't create self-repairing hiearchies of control. And you can't do things like use a debugger to attach to a process and terminate runaway goroutines.
At least for my operation it looked very much like I would really need to become a BEAM vm expert to make sure things ran smoothly (not just with that but other potential issues I had in the back of my mind as well).
From someone with zero experience in building concurrent systems: isn't this true for every sufficiently complex system? If your system is complex enough, then no general framework will help much, right?
I broke the deserialization up into 3 separate processes (1 for handling the I/O, 1 for packet deserialization, 1 for message deserialization) and while this fixed all the issues (presumably because it can balance the processes more effectively since no single process went over the reduction limit) it turned the effectively synchronous parsing process into a split async process and caused a lot of extra complexity around that.
I'm sure there's more to what caused the issue than just reduction limits but it also made me wary about the magic happening under the hood.