MPI_Comm_connect - Make a connection to another MPI process
#include <mpi.h> int MPI_Comm_connect(char *port_name, MPI_Info info, int root, MPI_Comm comm,
- - intercommunicator with server as remote group
The MPI_Comm_accept and MPI_Comm_connect calls simulate the well-understood accept() / connect() semantics of standard socket programming -- a client "connects" to a server.
LAM/MPI allows for previously-unrelated MPI programs to join into a MPI program with these calls. Both MPI programs must be running by the same user in the same LAM universe (i.e., in the scope of a single lamboot).
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.
USAGE WITH IMPI EXTENSIONS¶
The IMPI standard only supports MPI-1 functions. Hence, this function is currently not designed to operate within an IMPI job.
If an error occurs in an MPI function, the current MPI error handler is called to handle it. By default, this error handler aborts the MPI job. The error handler may be changed with MPI_Errhandler_set ; the predefined error handler MPI_ERRORS_RETURN may be used to cause error values to be returned (in C and Fortran; this error handler is less useful in with the C++ MPI bindings. The predefined error handler MPI::ERRORS_THROW_EXCEPTIONS should be used in C++ if the error value needs to be recovered). Note that MPI does not guarantee that an MPI program can continue past an error.
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. The C++ bindings for MPI do not return error values; instead, error values are communicated by throwing exceptions of type MPI::Exception (but not by default). Exceptions are only thrown if the error value is not MPI::SUCCESS .
Note that if the MPI::ERRORS_RETURN handler is set in C++, while MPI functions will return upon an error, there will be no way to recover what the actual error value was.
- - No error; MPI routine completed successfully.
- - Invalid communicator. A common error is to use a null communicator in a call (not even allowed in MPI_Comm_rank ).
- - Invalid root. The root must be specified as a rank in the communicator. Ranks must be between zero and the size of the communicator minus one.
- - Invalid argument. Some argument is invalid and is not identified by a specific error class. This is typically a NULL pointer or other such error.
- - An internal error has been detected. This is fatal. Please send a bug report to the LAM mailing list (see http://www.lam-mpi.org/contact.php ).
- - Other error; use MPI_Error_string to get more information about this error code.
- - Mismatch of run-time flags. For example, an MPI process that is running in lamd mode cannot spawn or be connected to a process that is running in c2c mode.
For more information, please see the official MPI Forum web site, which contains the text of both the MPI-1 and MPI-2 standards. These documents contain detailed information about each MPI function (most of which is not duplicated in these man pages).