mpi_comm_disconnect(3openmpi) [osx man page]
MPI_Comm_disconnect(3OpenMPI) MPI_Comm_disconnect(3OpenMPI) NAME
MPI_Comm_disconnect - Deallocates communicator object and sets handle to MPI_COMM_NULL. SYNTAX
C Syntax #include <mpi.h> int MPI_Comm_disconnect(MPI_Comm *comm) Fortran Syntax INCLUDE 'mpif.h' MPI_COMM_DISCONNECT(COMM, IERROR) INTEGER COMM, IERROR C++ Syntax #include <mpi.h> void MPI::Comm::Disconnect() INPUT
/OUTPUT PARAMETER comm Communicator (handle). OUTPUT PARAMETER
IERROR Fortran only: Error status (integer). DESCRIPTION
MPI_Comm_disconnect waits for all pending communication on comm to complete internally, deallocates the communicator object, and sets the handle to MPI_COMM_NULL. It is a collective operation. It may not be called with the communicator MPI_COMM_WORLD or MPI_COMM_SELF. MPI_Comm_disconnect may be called only if all communication is complete and matched, so that buffered data can be delivered to its destina- tion. This requirement is the same as for MPI_Finalize. MPI_Comm_disconnect has the same action as MPI_Comm_free, except that it waits for pending communication to finish internally and enables the guarantee about the behavior of disconnected processes. NOTES
To disconnect two processes you may need to call MPI_Comm_disconnect, MPI_Win_free, and MPI_File_close to remove all communication paths between the two processes. Note that it may be necessary to disconnect several communicators (or to free several windows or files) before two processes are completely independent. ERRORS
Almost all MPI routines return an error value; C routines as the value of the function and Fortran routines in the last argument. C++ func- tions do not return errors. If the default error handler is set to MPI::ERRORS_THROW_EXCEPTIONS, then on error the C++ exception mechanism will be used to throw an MPI:Exception object. Before the error value is returned, the current MPI error handler is called. By default, this error handler aborts the MPI job, except for I/O function errors. The error handler may be changed with MPI_Comm_set_errhandler; the predefined error handler MPI_ERRORS_RETURN may be used to cause error values to be returned. Note that MPI does not guarantee that an MPI program can continue past an error. SEE ALSO
MPI_Comm_connect MPI_Comm_accept Open MPI 1.2 September 2006 MPI_Comm_disconnect(3OpenMPI)
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MPI_Comm_size(3OpenMPI) MPI_Comm_size(3OpenMPI) NAME
MPI_Comm_size - Returns the size of the group associated with a communicator. SYNTAX
C Syntax #include <mpi.h> int MPI_Comm_size(MPI_Comm comm, int *size) Fortran Syntax INCLUDE 'mpif.h' MPI_COMM_SIZE(COMM, SIZE, IERROR) INTEGER COMM, SIZE, IERROR C++ Syntax #include <mpi.h> int Comm::Get_size() const INPUT PARAMETER
comm Communicator (handle). OUTPUT PARAMETERS
size Number of processes in the group of comm (integer). IERROR Fortran only: Error status (integer). DESCRIPTION
This function indicates the number of processes involved in a communicator. For MPI_COMM_WORLD, it indicates the total number of processes available. This function is equivalent to accessing the communicator's group with MPI_Comm_group, computing the size using MPI_Group_size, and then freeing the temporary group via MPI_Group_free. If the communicator is an intra-communicator (enables communication between two groups), this function returns the size of the local group. To return the size of the remote group, use the MPI_Comm_remote_size function. This call is often used with MPI_Comm_rank to determine the amount of concurrency available for a specific library or program. MPI_Comm_rank indicates the rank of the process that calls it in the range from 0 . . . size-1, where size is the return value of MPI_Comm_size. NOTE
MPI_COMM_NULL is not considered a valid argument to this function. ERRORS
Almost all MPI routines return an error value; C routines as the value of the function and Fortran routines in the last argument. C++ func- tions do not return errors. If the default error handler is set to MPI::ERRORS_THROW_EXCEPTIONS, then on error the C++ exception mechanism will be used to throw an MPI:Exception object. Before the error value is returned, the current MPI error handler is called. By default, this error handler aborts the MPI job, except for I/O function errors. The error handler may be changed with MPI_Comm_set_errhandler; the predefined error handler MPI_ERRORS_RETURN may be used to cause error values to be returned. Note that MPI does not guarantee that an MPI program can continue past an error. SEE ALSO
MPI_Comm_group MPI_Comm_rank MPI_Comm_compare Open MPI 1.2 September 2006 MPI_Comm_size(3OpenMPI)