The Great and Terrible implementation of MPI-2

function index


Gets the name of the processor
int MPI_Get_processor_name(
  char *name,
  int *resultlen

int MPI_Get_processor_name(
  wchar_t *name,
  int *resultlen


[out] A unique specifier for the actual (as opposed to virtual) node. This must be an array of size at least MPI_MAX_PROCESSOR_NAME.
[out] Length (in characters) of the name


The name returned should identify a particular piece of hardware; the exact format is implementation defined. This name may or may not be the same as might be returned by gethostname, uname, or sysinfo.

This routine returns the name of the processor on which it was called at the moment of the call. The name is a character string for maximum flexibility. From this value it must be possible to identify a specific piece of hardware; possible values include "processor 9 in rack 4 of" and "231" (where 231 is the actual processor number in the running homogeneous system). The argument name must represent storage that is at least MPI_MAX_PROCESSOR_NAME characters long. MPI_GET_PROCESSOR_NAME may write up to this many characters into name.

The number of characters actually written is returned in the output argument, resultlen.


This function allows MPI implementations that do process migration to return the current processor. Note that nothing in MPI requires or defines process migration; this definition of MPI_GET_PROCESSOR_NAME simply allows such an implementation.

Advice to users.

The user must provide at least MPI_MAX_PROCESSOR_NAME space to write the processor name --- processor names can be this long. The user should examine the ouput argument, resultlen, to determine the actual length of the name.

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.

In Fortran, the character argument should be declared as a character string of MPI_MAX_PROCESSOR_NAME rather than an array of dimension MPI_MAX_PROCESSOR_NAME. That is,

   character*(MPI_MAX_PROCESSOR_NAME) name
rather than
   character name(MPI_MAX_PROCESSOR_NAME)


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.

Example Code

The following sample code illustrates MPI_Get_processor_name.

#include "mpi.h"
#include <stdio.h>
int main(int argc, char *argv[])
    int rank, nprocs, len;
    char name[MPI_MAX_PROCESSOR_NAME];

    MPI_Get_processor_name(name, &len);
    printf("Hello, world.  I am %d of %d on %s\n", rank, nprocs, name);fflush(stdout);
return 0;