> ...Now you have two GCs running, neither of which knows about the other. ... For a strictly time-limited interaction (like what's involved in a FFI call) it'

> ...Now you have two GCs running, neither of which knows about the other. ... For a strictly time-limited interaction (like what's involved in a FFI call) it's not that bad. Everything that GC2 might directly access is temporarily promoted to a root for GC1, and vice versa.