The error codes returned by MPI are left entirely to the implementation (with the exception of MPI_SUCCESS). This is done to allow an implementation to provide as much information as possible in the error code (for use with MPI_ERROR_STRING).
To make it possible for an application to interpret an error code, the routine MPI_ERROR_CLASS converts any error code into one of a small set of standard error codes, called error classes. Valid error classes include
| MPI_SUCCESS | No error |
| MPI_ERR_BUFFER | Invalid buffer pointer |
| MPI_ERR_COUNT | Invalid count argument |
| MPI_ERR_TYPE | Invalid datatype argument |
| MPI_ERR_TAG | Invalid tag argument |
| MPI_ERR_COMM | Invalid communicator |
| MPI_ERR_RANK | Invalid rank |
| MPI_ERR_REQUEST | Invalid request (handle) |
| MPI_ERR_ROOT | Invalid root |
| MPI_ERR_GROUP | Invalid group |
| MPI_ERR_OP | Invalid operation |
| MPI_ERR_TOPOLOGY | Invalid topology |
| MPI_ERR_DIMS | Invalid dimension argument |
| MPI_ERR_ARG | Invalid argument of some other kind |
| MPI_ERR_UNKNOWN | Unknown error |
| MPI_ERR_TRUNCATE | Message truncated on receive |
| MPI_ERR_OTHER | Known error not in this list |
| MPI_ERR_INTERN | Internal MPI (implementation) error |
| MPI_ERR_IN_STATUS | Error code is in status |
| MPI_ERR_PENDING | Pending request |
| MPI_ERR_LASTCODE | Last error code |
The error classes are a subset of the error codes: an MPI function may return an error class number; and the function MPI_ERROR_STRING can be used to compute the error string associated with an error class.
The error codes satisfy,
0 = constMPI_SUCCESS < constMPI_ERR_... leq constMPI_ERR_LASTCODE.
Rationale.
The difference between MPI_ERR_UNKNOWN and MPI_ERR_OTHER is that MPI_ERROR_STRING can return useful information about MPI_ERR_OTHER.
Note that MPI_SUCCESS = 0 is necessary to be
consistent with C practice; the separation of error classes and error codes
allows us to define the error classes this way. Having a known
LASTCODE is often a nice sanity check as well.
( End of rationale.)
| MPI_ERROR_CLASS( errorcode, errorclass ) | |
| IN errorcode | Error code returned by an MPI routine |
| OUT errorclass | Error class associated with errorcode |
int MPI_Error_class(int errorcode, int *errorclass)
MPI_ERROR_CLASS(ERRORCODE, ERRORCLASS, IERROR)
INTEGER ERRORCODE, ERRORCLASS, IERROR
The function MPI_ERROR_CLASS maps each standard error code (error class) onto itself.