.TH MPI_Comm_get_parent 3 "11/10/2017" " " "MPI"

.SH NAME

MPI_Comm_get_parent \-  Return the parent communicator for this process 

.SH SYNOPSIS

.nf

int MPI_Comm_get_parent(MPI_Comm *parent)

.fi

.SH OUTPUT PARAMETERS

.PD 0

.TP

.B parent 

- the parent communicator (handle) 

.PD 1

.SH NOTES

If a process was started with 

.I MPI_Comm_spawn

or 

.I MPI_Comm_spawn_multiple

,

.I MPI_Comm_get_parent

returns the parent intercommunicator of the current

process. This parent intercommunicator is created implicitly inside of

.I MPI_Init

and is the same intercommunicator returned by 

.I MPI_Comm_spawn

in the parents.

If the process was not spawned, 

.I MPI_Comm_get_parent

returns

.I MPI_COMM_NULL

\&.

After the parent communicator is freed or disconnected, 

.I MPI_Comm_get_parent

returns 

.I MPI_COMM_NULL

\&.

.SH 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.

.SH NOTES FOR FORTRAN

All MPI routines in Fortran (except for 

.I MPI_WTIME

and 

.I MPI_WTICK

) have

an additional argument 

.I ierr

at the end of the argument list.  

.I ierr

is 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

.I call

statement.

All MPI objects (e.g., 

.I MPI_Datatype

, 

.I MPI_Comm

) are of type 

.I INTEGER

in Fortran.

.SH ERRORS

All MPI routines (except 

.I MPI_Wtime

and 

.I 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 

.I MPI_Comm_set_errhandler

(for communicators),

.I MPI_File_set_errhandler

(for files), and 

.I MPI_Win_set_errhandler

(for

RMA windows).  The MPI-1 routine 

.I MPI_Errhandler_set

may be used but

its use is deprecated.  The predefined error handler

.I MPI_ERRORS_RETURN

may be used to cause error values to be returned.

Note that MPI does 

.B not

guarentee that an MPI program can continue past

an error; however, MPI implementations will attempt to continue whenever

possible.

.PD 0

.TP

.B MPI_SUCCESS 

- No error; MPI routine completed successfully.

.PD 1

.PD 0

.TP

.B MPI_ERR_ARG 

- Invalid argument.  Some argument is invalid and is not

identified by a specific error class (e.g., 

.I MPI_ERR_RANK

).

.PD 1