DeinoMPI

The Great and Terrible implementation of MPI-2

MPI_Finalized

Indicates whether MPI_Finalize has been called.

int MPI_Finalized(
  int *flag
);

Parameters

flag: [out] Flag is true if MPI_Finalize has been called and false otherwise. (logical)

Remarks

This routine returns true if MPI_FINALIZE has completed. It is legal to call MPI_FINALIZED before MPI_INIT and after MPI_FINALIZE.

One of the goals of MPI was to allow for layered libraries. In order for a library to do this cleanly, it needs to know if MPI is active. In MPI-1 the function MPI_INITIALIZED was provided to tell if MPI had been initialized. The problem arises in knowing if MPI has been finalized. Once MPI has been finalized it is no longer active and cannot be restarted. A library needs to be able to determine this to act accordingly.

Advice to users.

MPI is "active" and it is thus safe to call MPI functions if MPI_INIT has completed and MPI_FINALIZE has not completed. If a library has no other way of knowing whether MPI is active or not, then it can use MPI_INITIALIZED and MPI_FINALIZED to determine this. For example, MPI is "active" in callback functions that are invoked during MPI_FINALIZE.

Thread and Interrupt Safety

This routine is both thread- and interrupt-safe. This means that this routine may safely be used by multiple threads and from within a signal handler.

Notes for Fortran

All MPI routines in Fortran (except for MPI_WTIME and MPI_WTICK) have an additional argument ierr at the end of the argument list. ierris an integer and has the same meaning as the return value of the routine in C. In Fortran, MPI routines are subroutines, and are invoked with the call statement. All MPI objects (e.g., MPI_Datatype, MPI_Comm) are of type INTEGERin Fortran.

Errors

All MPI routines (except MPI_Wtime and MPI_Wtick) return an error value; C routines as the value of the function and Fortran routines in the last argument. Before the value is returned, the current MPI error handler is called. By default, this error handler aborts the MPI job. The error handler may be changed with MPI_Comm_set_errhandler (for communicators), MPI_File_set_errhandler (for files), and MPI_Win_set_errhandler (for RMA windows). The MPI-1 routine MPI_Errhandler_set may be used but its use is deprecated. The predefined error handler MPI_ERRORS_RETURN may be used to cause error values to be returned. Note that MPI does not guarentee that an MPI program can continue past an error; however, MPI implementations will attempt to continue whenever possible.

MPI_SUCCESS: No error; MPI routine completed successfully.

Example Code

The following sample code illustrates MPI_Finalized.

#include "mpi.h"
#include <stdio.h>
int main( int argc, char *argv[] )
{
    int flag;

    flag = 0;
    MPI_Finalized(&flag);
    if (flag)
    {
        printf("MPI_Finalized returned true before MPI_Init.\n");
        return -1;
    }

    MPI_Init(&argc, &argv);

    flag = 0;
    MPI_Finalized(&flag);
    if (flag)
    {
        printf("MPI_Finalized returned true before MPI_Finalize.\n");
        fflush(stdout);
        MPI_Abort(MPI_COMM_WORLD, 1);
        return -1;
    }

    MPI_Finalize();

    flag = 0;
    MPI_Finalized(&flag);
    if (!flag)
    {
        printf("MPI_Finalized returned false after MPI_Finalize.\n");
        return -1;
    }
    return 0;
}

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