Synopsis

int MPI_Probe(int source, int tag, MPI_Comm comm, MPI_Status *status)

Input Parameters

source

rank of source or MPI_ANY_SOURCE (integer)

tag

message tag or MPI_ANY_TAG (integer)

comm

communicator (handle)

Output Parameters

status

status object (Status)

Thread and Interrupt Safety

This routine is thread-safe. This means that this routine may be safely used by multiple threads without the need for any user-provided thread locks. However, the routine is not interrupt safe. Typically, this is due to the use of memory allocation routines such as 'malloc' or other non-MPICH runtime routines that are themselves not interrupt-safe.

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

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. Before the value is returned, the current MPI error handler is called. By default, this error handler aborts the MPI job. The error handler may be changed with 'MPI_Comm_set_errhandler' (for communicators), 'MPI_File_set_errhandler' (for files), and 'MPI_Win_set_errhandler' (for RMA windows). The MPI-1 routine 'MPI_Errhandler_set' may be used but its use is deprecated. 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; however, MPI implementations will attempt to continue whenever possible.

  • MPI_SUCCESS - No error; MPI routine completed successfully.

  • MPI_ERR_ARG - Invalid argument. Some argument is invalid and is not identified by a specific error class (e.g., 'MPI_ERR_RANK').

  • MPI_ERR_COMM - Invalid communicator. A common error is to use a null communicator in a call (not even allowed in 'MPI_Comm_rank').

  • MPI_ERR_RANK - Invalid source or destination rank. Ranks must be between zero and the size of the communicator minus one; ranks in a receive ('MPI_Recv', 'MPI_Irecv', 'MPI_Sendrecv', etc.) may also be 'MPI_ANY_SOURCE'.

  • MPI_ERR_TAG - Invalid tag argument. Tags must be non-negative; tags in a receive ('MPI_Recv', 'MPI_Irecv', 'MPI_Sendrecv', etc.) may also be 'MPI_ANY_TAG'. The largest tag value is available through the the attribute 'MPI_TAG_UB'.

  • MPI_ERR_OTHER - Other error; use 'MPI_Error_string' to get more information about this error code.