The Great and Terrible implementation of MPI-2

function index


Create a communicator error handler
int MPI_Comm_create_errhandler(
  MPI_Comm_errhandler_fn *function,
  MPI_Errhandler *errhandler

Input Parameter

[in] user defined error handling procedure (function)
[out] MPI error handler (handle)


Creates an error handler that can be attached to communicators. This function is identical to MPI_ERRHANDLER_CREATE, whose use is deprecated.

The user routine should be, in C, a function of type MPI_Comm_errhandler_fn, which is defined as

typedef void MPI_Comm_errhandler_fn(MPI_Comm *, int *, ...);

The first argument is the communicator in use, the second is the error code to be returned. This typedef replaces MPI_Handler_function, whose use is deprecated.

In Fortran, the user routine should be of the form:


In C++, the user routine should be of the form:

typedef void MPI::Comm::Errhandler_fn(MPI::Comm &, int *, ... );

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.


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 guarentee that an MPI program can continue past an error; however, MPI implementations will attempt to continue whenever possible.

No error; MPI routine completed successfully.
Invalid communicator. A common error is to use a null communicator in a call (not even allowed in MPI_Comm_rank).
Other error; use MPI_Error_string to get more information about this error code.

Example Code

The following sample code illustrates MPI_Comm_create_errhandler.

#include "mpi.h"
#include <stdio.h>

static int calls = 0;
static int errs = 0;
static MPI_Comm mycomm;

void eh( MPI_Comm *comm, int *err, ... )
    if (*err != MPI_ERR_OTHER) {
        printf( "Unexpected error code\n" );fflush(stdout);
if (*comm != mycomm) {
        printf( "Unexpected communicator\n" );fflush(stdout);

int main( int argc, char *argv[] )
    MPI_Comm comm;
    MPI_Errhandler newerr;

    MPI_Init( &argc, &argv );
    comm = MPI_COMM_WORLD;
    mycomm = comm;
    MPI_Comm_create_errhandler( eh, &newerr );
    MPI_Comm_set_errhandler( comm, newerr );
    MPI_Comm_call_errhandler( comm, MPI_ERR_OTHER );
    MPI_Errhandler_free( &newerr );
if (calls != 1) {
        printf( "Error handler not called\n" );fflush(stdout);
return 0;