MPI and global variables

Question

I have to implement an MPI program. There are some global variables (4 arrays of float numbers and other 6 single float variables) which are first inizialized by the main pr

Answer 1

When MPI_Init() is called all processes are created by fork right?

Wrong.

MPI spawns multiple instances of your program. These instances are separate processes, each with its own memory space. Each process has its own copy of every variable, including globals. MPI_Init() only initializes the MPI environment so that other MPI functions can be called.