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MPI_Comm_free_keyval(3OpenMPI)                                                MPI_Comm_free_keyval(3OpenMPI)



NAME
       MPI_Comm_free_keyval - Frees attribute key for communicator cache attribute.


SYNTAX
C Syntax
       #include <mpi.h>
       int MPI_Comm_free_keyval(int *comm_keyval)


Fortran Syntax
       INCLUDE 'mpif.h'
       MPI_COMM_FREE_KEYVAL(COMM_KEYVAL, IERROR)
            INTEGER   COMM_KEYVAL, IERROR


C++ Syntax
       #include <mpi.h>
       static void MPI::Comm::Free_keyval(int& comm_keyval)


INPUT/OUTPUT PARAMETER
       comm_keyval


OUTPUT PARAMETER
       IERROR    Fortran only: Error status (integer).



DESCRIPTION
       MPI_Comm_free_keyval  frees  an  extant  attribute  key.  This  function  sets the value of keyval to
       MPI_KEYVAL_INVALID. Note that it is not erroneous to free an attribute key that is  in  use,  because
       the actual free does not transpire until after all references (in other communicators on the process)
       to the key have been freed. These references need to be explictly freed by the  program,  either  via
       calls  to  MPI_Comm_delete_attr  that  free one attribute instance, or by calls to MPI_Comm_free that
       free all attribute instances associated with the freed communicator.

       This call is identical to the call MPI_Keyval_free but is needed to match the   communicator-specific
       creation function introduced in the MPI-2 standard. The use of MPI_Keyval_free is deprecated.



NOTES
       Key values are global (they can be used with any and all communicators).


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++ functions 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.




Open MPI 1.2                                   September 2006                 MPI_Comm_free_keyval(3OpenMPI)