NAME

       MPI_Request_free -  Frees a communication request object

SYNOPSIS

       #include <mpi.h>
       int MPI_Request_free(MPI_Request *preq)

INPUT PARAMETER

       preq   - communication request (handle)

NOTES

       This   routine   is  normally  used  to  free  persistent  requests  created  with  either
       MPI_Recv_init or MPI_Send_init (and friends).  However, it can be used to free  a  request
       created  with  MPI_Irecv or MPI_Isend (and friends); in that case the user can not use the
       test/wait routines on the request.

       It is permitted to free an active request.  However, once  freed,  you  can  not  use  the
       request in a wait or test routine (e.g., MPI_Wait ).

       preq is set to MPI_REQUEST_NULL upon completion.

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

       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.
       MPI_SUCCESS
              - No error; MPI routine completed successfully.
       MPI_ERR_REQUEST
              -  Invalid  MPI_Request  ;  either  null  or,  MPI_REQUEST_NULL  , in the case of a
              MPI_Start or MPI_Startall , not a persistent request.
       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.

SEE ALSO

       also:   MPI_Isend,   MPI_Irecv,   MPI_Issend,   MPI_Ibsend,   MPI_Irsend,   MPI_Recv_init,
       MPI_Send_init,   MPI_Ssend_init,   MPI_Rsend_init,   MPI_Wait,   MPI_Test,    MPI_Waitall,
       MPI_Waitany, MPI_Waitsome, MPI_Testall, MPI_Testany, MPI_Testsome

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

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

ACKNOWLEDGEMENTS

       The  LAM  Team  would  like the thank the MPICH Team for the handy program to generate man
       pages  ("doctext"  from  ftp://ftp.mcs.anl.gov/pub/sowing/sowing.tar.gz  ),  the   initial
       formatting, and some initial text for most of the MPI-1 man pages.

LOCATION

       reqfree.c