NAME

MPI_Abort - Terminates MPI execution environment

SYNOPSIS

#include <mpi.h>
int MPI_Abort(MPI_Comm comm, int errcode)

INPUT PARAMETERS

comm

- communicator of tasks to abort

errcode

- error code to return to invoking environment

NOTES

Makes a "best attempt" to terminate all MPI processes associated with the communicator comm ; for non-IMPI jobs, this will terminate all processes. MPI_Abort will hang, however, if the LAM daemon on the node on which a rank was running has died. For example, if a node gets powered off in the middle of an MPI run and MPI_Abort is invoked, it may hang trying to contact the LAM daemon on the downed node.

In the case of an IMPI job, in addition to terminating all local IMPI procs, this function will also send an abort message to the local IMPI host, which will, in turn send "closing" messages to all the other IMPI hosts. Their behavior upon receipt of these "closing" messages is implementation dependant.

If the LAM IMPI host receives a premature "closing" message from a remote IMPI host, it will attempt to continue processing. Any new messages to that host will likely hang, however.

'ERRCODE' IS SPLIT INTO THREE SECTIONS

lower 8 bits: error class

- . next 9 bits: function enumeration (there are over 300 MPI functions; it takes 9 bits to represent all possibilities)

upper 15 bits: error code

- If the error class is nonzero, the error code is the POSIX return value for the program (i.e., exit(error_code) is eventually called to terminate the program). If the error class is zero, errcode is returned as the POSIX return value for the program.

This is mainly because MPI_Abort is used internally in LAM/MPI to abort MPI upon error; LAM packs all three pieces of data into the errcode. Users who wish to return a specific value from the program

SHOULD USE SOMETHING SIMILAR TO

return ((return_code << 17) + 1);

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.

MORE INFORMATION

For more information, please see the official MPI Forum web site, which contains the text of both the MPI-1 and MPI-2 standards. These documents contain detailed information about each MPI function (most of which is not duplicated in these man pages).

http://www.mpi-forum.org/

ACKNOWLEDGEMENTS

The LAM Team would like the thank the MPICH Team for the handy program to generate man pages ("doctext" from ftp://ftp.mcs.anl.gov/pub/sowing/sowing.tar.gz ), the initial formatting, and some initial text for most of the MPI-1 man pages.

LOCATION

abort.c