# MPI_Comm_get_parent

Return the parent communicator for this process

## Synopsis

    int MPI_Comm_get_parent(MPI_Comm *parent)

## Output Parameters

parent
  the parent communicator (handle)

## Notes

If a process was started with `MPI_Comm_spawn` or `MPI_Comm_spawn_multiple`, `MPI_Comm_get_parent` returns the parent intercommunicator of the current process. This parent intercommunicator is created implicitly inside of `MPI_Init` and is the same intercommunicator returned by `MPI_Comm_spawn` in the parents.

If the process was not spawned, `MPI_Comm_get_parent` returns `MPI_COMM_NULL`.

After the parent communicator is freed or disconnected, `MPI_Comm_get_parent` returns `MPI_COMM_NULL`.

## 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. `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 `call` statement.

All MPI objects (e.g., `MPI_Datatype`, `MPI_Comm`) are of type `INTEGER` in 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.

MPI_ERR_ARG
  Invalid argument. Some argument is invalid and is not identified by a specific error class (e.g., `MPI_ERR_RANK`).