Process-per-connection with drb

Reading through drb.rb, I see that drb uses a thread-per-connection
model. I have some C++ extensions that I want to provide access to via
a drb server. Unfortunately, these extensions are not safe to use with
ruby’s green threads, and it is impossible to make them thread-safe,
given the mechanism ruby uses to switch thread contexts.

I want to instead use a process-per-connection model and have a pool of
processes waiting to handle requests. How should I go about
implementing this?