Appendix B Troubleshooting

This appendix describes some common problem situations, resulting error messages, and suggestions for fixing the problems. Sun MPI error reporting, including I/O, follows the MPI-2 standard. By default, errors are reported in the form of standard error classes. These classes and their meanings are listed in Table B-1 (for non-I/O MPI) and Table B-2 (for MPI I/O) and are also available on the MPI man page.

Three predefined error handlers are available in Sun MPI 4.0:

• MPI_ERRORS_RETURN - The default, returns an error code if an error occurs.

• MPI_ERRORS_ARE_FATAL - I/O errors are fatal, and no error code is returned.

• MPI_THROW_EXCEPTION - A special error handler to be used only with C⁺⁺.

MPI Messages

You can make changes to and get information about the error handler using any of the following routines:

• MPI_Comm_create_errhandler

• MPI_Comm_get_errhandler

• MPI_Comm_set_errhandler

Messages resulting from an MPI program fall into two categories:

• Error messages - Error messages stem from within MPI. Usually an error message explains why your program cannot complete, and the program aborts.

• Warning messages - Warnings stem from the environment in which you are running your MPI program and are usually sent by MPI_Init. They are not associated with an aborted program, that is, programs continue to run despite warning messages.

Error Messages

Sun MPI error messages use a standard format:

[x y z] Error in function_name: errclass_string:intern(a):description:unixerrstring

where

• [x y z] is the process communication identifier, and:

  • x is the job id (or jid).

  • y is the name of the communicator if a name exists; otherwise it is the address of the opaque object.

  • z is the rank of the process.

    The process communication identifier is present in every error message.

• function_name is the name of the associated MPI function. It is present in every error message.

• errclass_string is the string associated with the MPI error class. It is present in every error message.

• intern is an internal function. It is optional.

• a is a system call, if one is the cause of the error. It is optional.

• description is a description of the error. It is optional.

• unixerrstring is the UNIX error string that describes system call a. It is optional.

Warning Messages

Sun MPI warning messages also use a standard format:

[x y z] Warning message

where

• message is a description of the error.

Standard Error Classes

Listed below are the error return classes you may encounter in your MPI programs. Error values may also be found in mpi.h (for C), mpif.h (for Fortran), and mpi++.h (for C⁺⁺).

Table B-1 Sun MPI Standard Error Classes

Error Code	Value	Meaning
MPI_SUCCESS	0	Successful return code.
MPI_ERR_BUFFER	1	Invalid buffer pointer.
MPI_ERR_COUNT	2	Invalid count argument.
MPI_ERR_TYPE	3	Invalid datatype argument.
MPI_ERR_TAG	4	Invalid tag argument.
MPI_ERR_COMM	5	Invalid communicator.
MPI_ERR_RANK	6	Invalid rank.
MPI_ERR_ROOT	7	Invalid root.
MPI_ERR_GROUP	8	Null group passed to function.
MPI_ERR_OP	9	Invalid operation.
MPI_ERR_TOPOLOGY	10	Invalid topology.
MPI_ERR_DIMS	11	Illegal dimension argument.
MPI_ERR_ARG	12	Invalid argument.
MPI_ERR_UNKNOWN	13	Unknown error.
MPI_ERR_TRUNCATE	14	Message truncated on receive.
MPI_ERR_OTHER	15	Other error; use Error_string.
MPI_ERR_INTERN	16	Internal error code.
MPI_ERR_IN_STATUS	17	Look in status for error value.
MPI_ERR_PENDING	18	Pending request.
MPI_ERR_REQUEST	19	Illegal MPI_Request handle.
MPI_ERR_KEYVAL	36	Illegal key value.
MPI_ERR_INFO	37	Invalid info object.
MPI_ERR_INFO_KEY	38	Illegal info key.
MPI_ERR_INFO_NOKEY	39	No such key.
MPI_ERR_INFO_VALUE	40	Illegal info value.
MPI_ERR_TIMEDOUT	41	Timed out.
MPI_ERR_RESOURCES	42	Out of resources.
MPI_ERR_TRANSPORT	43	Transport layer error.
MPI_ERR_HANDSHAKE	44	Error accepting/connecting.
MPI_ERR_SPAWN	45	Error spawning.
MPI_ERR_LASTCODE	46	Last error code.

MPI I/O message are listed separately, in Table B-2.

MPI I/O Error Handling

Sun MPI I/O error reporting follows the MPI-2 standard. By default, errors are reported in the form of standard error codes (found in /opt/SUNWhpc/include/mpi.h). Error classes and their meanings are listed in Table B-2. They can also be found in mpif.h (for Fortran) and mpi++.h (for C⁺⁺).

You can change the default error handler by specifying MPI_FILE_NULL as the file handle with the routine MPI_File_set_errhandler, even no file is currently open. Or, you can use the same routine to change a specific file's error handler.

Table B-2 Sun MPI I/O Error Classes

Error Class	Value	Meaning
MPI_ERR_FILE	20	Bad file handle.
MPI_ERR_NOT_SAME	21	Collective argument not identical on all processes.
MPI_ERR_AMODE	22	Unsupported amode passed to open.
MPI_ERR_UNSUPPORTED_DATAREP	23	Unsupported datarep passed to MPI_File_set_view.
MPI_ERR_UNSUPPORTED_OPERATION	24	Unsupported operation, such as seeking on a file that supports only sequential access.
MPI_ERR_NO_SUCH_FILE	25	File (or directory) does not exist.
MPI_ERR_FILE_EXISTS	26	File exists.
MPI_ERR_BAD_FILE	27	Invalid file name (for example, path name too long).
MPI_ERR_ACCESS	28	Permission denied.
MPI_ERR_NO_SPACE	29	Not enough space.
MPI_ERR_QUOTA	30	Quota exceeded.
MPI_ERR_READ_ONLY	31	Read-only file system.
MPI_ERR_FILE_IN_USE	32	File operation could not be completed, as the file is currently open by some process.
MPI_ERR_DUP_DATAREP	33	Conversion functions could not be registered because a data representation identifier that was already defined was passed to MPI_REGISTER_DATAREP.
MPI_ERR_CONVERSION	34	An error occurred in a user-supplied data-conversion function.
MPI_ERR_IO	35	I/O error.
MPI_ERR_INFO	37	Invalid info object.
MPI_ERR_INFO_KEY	38	Illegal info key.
MPI_ERR_INFO_NOKEY	39	No such key .
MPI_ERR_INFO_VALUE	40	Illegal info value.
MPI_ERR_LASTCODE	46	Last error code.