Support for posix-spawn?

Would it be possible to use posix-spawn for shell commands?

It's more efficient than popen3 and provides meaningful process hierarchies because it performs a single fork/exec. (popen3 double forks to avoid needing to collect the exit status and also calls Process::detach which creates a Ruby Thread!!!!).

It handles all max pipe buffer (PIPE_BUF) hang cases when reading and writing semi-large amounts of data. This is non-trivial to implement correctly and must be accounted for with popen3, spawn, or hand rolled fork/exec code.

It's more portable than hand rolled pipe, fork, exec code because fork(2) and exec aren't available on all platforms. In those cases, POSIX::Spawn::Child falls back to using whatever janky substitutes the platform provides.