I know this is quite along time after the original post. However, I figured it is reasonable to note that you can send in an MPI communicator to the Expression class as a keyword argument, as shown in: Error with IO in parallel - - #4 by dokken
I know this is quite along time after the original post. However, I figured it is reasonable to note that you can send in an MPI communicator to the Expression class as a keyword argument, as shown in: Error with IO in parallel - - #4 by dokken