program deadlock
      implicit none
      include 'mpif.h'
      integer MSGLEN, ITAG_A, ITAG_B
      parameter (MSGLEN = 2048, ITAG_A = 100, ITAG_B = 200)
      real rmsg1(MSGLEN), rmsg2(MSGLEN)
      integer irank, idest, isrc, istag, iretag,istatus(MPI_STATUS_SIZE)
      integer ierr, I

      call MPI_Init (ierr)
      call MPI_Comm_rank( MPI_COMM_WORLD, irank, ierr)
      
      do I = 1, MSGLEN
        rmsg1(I) = 100
        rmsg2(I) = -100
      end do
      
      if ( irank .eq. 0 ) then 
        idest  = 1
        isrc   = 1
        istag  = ITAG_A
        iretag = ITAG_B
      else if ( irank .eq. 1 ) then  
        idest  = 0
        isrc   = 0
        istag  = ITAG_B
        iretag = ITAG_A
      end if
      
      print *, "Task ", irank, " has sent the message "
      call MPI_Ssend (rmsg1,MSGLEN, MPI_REAL, idest, istag, 
     *  MPI_COMM_WORLD, ierr)
      call MPI_Recv (rmsg2, MSGLEN, MPI_REAL, isrc, iretag, 
     *  MPI_COMM_WORLD,istatus, ierr)
      print*, "Task", irank, " has received the message " 
      call MPI_Finalize (ierr)
      end