The MPI standard allows requests to be ``freed'' by the user at any time with
the MPI_Request_free call.
This means that the user will never issue a wait or test call with this
request. However, the MPI implementation must still complete the operation
and recover the space used by the request itself (the user is responsible for
not using the data buffers improperly). Note that MPI_Request_free is
not like a MPI_Wait call; it is a local call. To inform the ADI
that the request is being released, the additional functions
MPID_SendFree( handle ) MPID_RecvFree( handle )are defined. Once a handle has been given as an argument to one of these routines, it is the responsibility of the device to free the request structure.