MPI_Cancel function

Cancels a communication request.

Syntax

int MPIAPI MPI_Cancel(
  _In_ MPI_Request *request
);

Parameters

• request [in]
  Communication request.

Return value

Returns MPI_SUCCESS on success. Otherwise, the return value is an error code.

In Fortran, the return value is stored in the IERROR parameter.

Fortran

    MPI_CANCEL(REQUEST, IERROR)
        INTEGER REQUEST, IERROR

Remarks

The primary expected use of MPI_Cancel is in multi-buffering schemes, where speculative MPI_Irecvs are made. When the computation completes, some of these receive requests may remain; using MPI_Cancel allows the user to cancel these unsatisfied requests.

Cancelling a send operation is much more difficult, in large part because the send will usually be at least partially complete (the information on the tag, size, and source are usually sent immediately to the destination). Users are advised that cancelling a send, while a local operation (as defined by the MPI standard), is likely to be expensive (usually generating one or more internal messages).

Requirements

See also

MPI Point to Point Functions