DeinoMPI

The Great and Terrible implementation of MPI-2

MPI_Open_port

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

int MPI_Open_port(
  MPI_Info info,
  char *port_name
);

int MPI_Open_port(
  MPI_Info info,
  wchar_t *port_name
);

Parameters

info: [in] implementation-specific information on how to establish a port for MPI_Comm_accept (handle)
port_name: [out] newly established port (string)

Remarks

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.

This function establishes a network address, encoded in the port_name string, at which the server will be able to accept connections from clients. port_name is supplied by the system, possibly using information in the info argument.

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.
Advice to users.

The system copies the port name into port_name. The application must pass a buffer of sufficient size to hold this value.

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 mallocor 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. ierris 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 INTEGERin 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.

Example Code

The following sample code illustrates MPI_Open_port.

#include "mpi.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <windows.h> /* Sleep */

/* This test checks to make sure that two MPI_Comm_connects to two different MPI ports
* match their corresponding MPI_Comm_accepts. The root process opens two MPI ports and
* sends the first port to process 1 and the second to process 2. Then the root process
* accepts a connection from the second port followed by the first port.
* Processes 1 and 2 both connect back to the root but process 2 first sleeps for three
* seconds to give process 1 time to attempt to connect to the root. The root should wait
* until process 2 connects before accepting the connection from process 1.
*/
int main( int argc, char *argv[] )
{
    int num_errors = 0;
    int rank, size;
    char port1[MPI_MAX_PORT_NAME];
    char port2[MPI_MAX_PORT_NAME];
    MPI_Status status;
    MPI_Comm comm1, comm2;
    int data = 0;

    MPI_Init(&argc, &argv);
    MPI_Comm_size(MPI_COMM_WORLD, &size);
    MPI_Comm_rank(MPI_COMM_WORLD, &rank);
    if (size < 3)
    {
        printf("Three processes needed to run this test.\n");fflush(stdout);
        MPI_Finalize();
        return 0;
    }

    if (rank == 0)
    {
        printf("0: opening ports.\n");fflush(stdout);
        MPI_Open_port(MPI_INFO_NULL, port1);
        MPI_Open_port(MPI_INFO_NULL, port2);
        printf("opened port1: <%s>\n", port1);
        printf("opened port2: <%s>\n", port2);fflush(stdout);

        MPI_Send(port1, MPI_MAX_PORT_NAME, MPI_CHAR, 1, 0, MPI_COMM_WORLD);
        MPI_Send(port2, MPI_MAX_PORT_NAME, MPI_CHAR, 2, 0, MPI_COMM_WORLD);

        printf("accepting port2.\n");fflush(stdout);
        MPI_Comm_accept(port2, MPI_INFO_NULL, 0, MPI_COMM_SELF, &comm2);
        printf("accepting port1.\n");fflush(stdout);
        MPI_Comm_accept(port1, MPI_INFO_NULL, 0, MPI_COMM_SELF, &comm1);
        MPI_Close_port(port1);
        MPI_Close_port(port2);

        printf("sending 1 to process 1.\n");fflush(stdout);
        data = 1;
        MPI_Send(&data, 1, MPI_INT, 0, 0, comm1);
        printf("sending 2 to process 2.\n");fflush(stdout);
        data = 2;
        MPI_Send(&data, 1, MPI_INT, 0, 0, comm2);

        MPI_Comm_disconnect(&comm1);
        MPI_Comm_disconnect(&comm2);
    }
    else if (rank == 1)
    {
        MPI_Recv(port1, MPI_MAX_PORT_NAME, MPI_CHAR, 0, 0, MPI_COMM_WORLD, &status);
        MPI_Comm_connect(port1, MPI_INFO_NULL, 0, MPI_COMM_SELF, &comm1);
        MPI_Recv(&data, 1, MPI_INT, 0, 0, comm1, &status);
        if (data != 1)
        {
            printf("Received %d from root when expecting 1\n", data);
            fflush(stdout);
            num_errors++;
        }
        MPI_Comm_disconnect(&comm1);
    }
    else if (rank == 2)
    {
        MPI_Recv(port2, MPI_MAX_PORT_NAME, MPI_CHAR, 0, 0, MPI_COMM_WORLD, &status);
        /* make sure process 1 has time to do the connect before this process attempts to connect */
        Sleep(3000);
        MPI_Comm_connect(port2, MPI_INFO_NULL, 0, MPI_COMM_SELF, &comm2);
        MPI_Recv(&data, 1, MPI_INT, 0, 0, comm2, &status);
        if (data != 2)
        {
            printf("Received %d from root when expecting 2\n", data);
            fflush(stdout);
            num_errors++;
        }
        MPI_Comm_disconnect(&comm2);
    }
    MPI_Barrier(MPI_COMM_WORLD);
    MPI_Finalize();
    return 0;
}

DOWNLOAD

Win32 DeinoMPI.2.0.1.msi
Win64 DeinoMPI.x64.2.0.1.msi