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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