# MPI_Open_port

Establish an address that can be used to establish connections between groups of MPI processes

## Synopsis

    int MPI_Open_port(MPI_Info info, char *port_name)

## Input Parameters

info
  implementation-specific information on how to establish a port for `MPI_Comm_accept` (handle)

## Output Parameters

port_name
  newly established port (string)

## Notes

MPI copies a system-supplied port name into `port_name`. `port_name` identifies the newly opened port and can be used by a client to contact the server. The maximum size string that may be supplied by the system is `MPI_MAX_PORT_NAME`.

## Reserved Info Key Values

ip_port
  Value contains IP port number at which to establish a port.
ip_address
  Value contains IP address at which to establish a port. If the address is not a valid IP address of the host on which the `MPI_OPEN_PORT` call is made, the results are undefined.

## Thread and Interrupt Safety

This routine is thread-safe. This means that this routine may be safely used by multiple threads without the need for any user-provided thread locks. However, the routine is not interrupt safe. Typically, this is due to the use of memory allocation routines such as `malloc` or other non-MPICH runtime routines that are themselves not interrupt-safe.

## 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.