[yellowapple]

That doesn't sound right re: Erlang; its everything-is-immutable model is supposed to avoid the need for a GIL. Erlang processes are also preemptive, so there's no possibility for a process to lock up the whole VM (unless it calls into a long-running NIF, but native code is always dangerous in a "crash BEAM if you don't get it right" kind of way).

[dragonwriter]

IIRC, Erlang uses shared mutable state internally, though its not exposed, so it needs to lock around accesses to that, but this isn't equivalent to the Python GIL.