Initialize the MPI execution environment
int MPI_Init( int *argc, char ***argv )
- Pointer to the number of arguments
- Pointer to the argument vector
Thread and Signal Safety
This routine must be called by one thread only. That thread is called
the main thread and must be the thread that calls MPI_Finalize.
The MPI standard does not say what a program can do before an MPI_INIT or
after an MPI_FINALIZE. In the MPICH implementation, you should do
as little as possible. In particular, avoid anything that changes the
external state of the program, such as opening files, reading standard
input or writing to standard output.
Notes for C
As of MPI-2, MPI_Init will accept NULL as input parameters. Doing so
will impact the values stored in MPI_INFO_ENV.
Notes for Fortran
The Fortran binding for MPI_Init has only the error return
subroutine MPI_INIT( ierr )
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
- No error; MPI routine completed successfully.
- This error class is associated with an error code that
indicates that an attempt was made to call MPI_INIT a second time.
MPI_INIT may only be called once in a program.