Rmpi program hangs after producing correct output. How do I exit programatically?

Question

The code I am using is:

library(Rmpi)
mpi.spawn.Rslaves(nslaves=mpi.universe.size()-1)
mpi.remote.exec(paste(--))
mpi.close.Rslaves()
mpi.quit()

I tried mpi.exit() but still, it hangs.