MPI_Comm_join  -   Connect  two  MPI processed joined by a
       socket


SYNOPSIS

       #include <mpi.h>
       int
       MPI_Comm_join(int fd, MPI_Comm *newcomm)


INPUT PARAMETER

       fd     - socket file descriptor


OUTPUT PARAMETER

       newcomm
              - intercommunicator with client as remote group


DESCRIPTION

       This function only works  between  two  LAM/MPI  processes
       that are connected by a socket.  They either must have the
       same endian orientation, or not have used the  homogeneous
       flag to mpirun (1) (-O).  Both processes must be in a sin­
       gle LAM universe -- they must share LAM daemons  that  are
       already  connected  to  each  other.   That  is, they were
       either initially lamboot(1)ed together,  or  a  lamgrow(1)
       command  was  given  to  grow an initial LAM universe such
       that the resulting set includes the two hosts in question.

       Once  this call completes successfully, fd may not be used
       by the caller for any reason.  LAM will  eventually  close
       the  socket (possibly as late as during MPI_Finalize (3)).


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 For­
       tran, 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.


ERRORS

       If an error occurs in an MPI  function,  the  current  MPI

       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  val­
       ues  to  be returned (in C and Fortran; this error handler
       is less useful in with the C++ MPI bindings.   The  prede­
       fined 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++  bind­
       ings  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.
       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.  This
              is typically a NULL pointer or other such error.
       MPI_ERR_INTERN
              - 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 ).
       MPI_ERR_OTHER
              - Other error; use  MPI_Error_string  to  get  more
              information about this error code.


SEE ALSO

       lamboot(1), lamgrow(1), mpirun(1), MPI_Finalize(3)


MORE INFORMATION

       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 infor­
       mation about each MPI  function  (most  of  which  is  not
       duplicated in these man pages).

       http://www.mpi-forum.org/


LOCATION

       join.c


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