0,1,mpi_comm_world,request(1),ierr)
                i=i+1
                print *,i
                vec=-vec
                call usleep_fortran(2.d0)
                call mpi_wait(request(1),MPI_STATUS_IGNORE,ierr)
        end do

end program send
--------------------------------------------------
#2
program send
implicit none
        include 'mpif.h'

real*8 :: vec(20000)
integer :: ierr

        call mpi_init(ierr)
        do
                if(key_present()) then
                        call mpi_recv(vec,20000,mpi_real8,1,1,mpi_comm_world,MPI_STATUS_IGNORE,ierr)
                end if
                call usleep_fortran(0.05d0)

        end do

contains

function key_present()
implicit none
logical :: key_present

        key_present = .false.
        call mpi_iprobe(1,1,mpi_comm_world,key_present,MPI_STATUS_IGNORE,ierr)
        print *, key_present

end function key_present

end program send
-----------------------------------
The usleep_fortran is a routine I've written to pause the program for that amount of time (in seconds). As you can see, on the receiving end I'm probing to see whether the message has being received every 0.05 seconds, where each probing would result a print of the probing result; while the sending is once every 2 seconds.

Doing
mpirun -np 1 recv : -np 1 send
Naturally I expect the output to be something like:

1
(fourty or so F)
T
2
(another fourty or so F)
T
3

however this is the output I get:

1
(fourty or so F)
T
2
(about a two second delay)
T
3

It seems to me that after the first set of probes, once the message was received, the non-blocking mpi probe becomes blocking for some strange reason. I'm using mpi_iprobe for the first time, so I'm not sure if I'm doing something blatantly wrong.