MPI_Comm_get_attr(3) Open MPI MPI_Comm_get_attr(3)

MPI_Comm_get_attr - Retrieves attribute value by key.

#include <mpi.h>
int MPI_Comm_get_attr(MPI_Comm comm, int comm_keyval,
	void *attribute_val, int *flag)

USE MPI
! or the older form: INCLUDE 'mpif.h'
MPI_COMM_GET_ATTR(COMM, COMM_KEYVAL, ATTRIBUTE_VAL, FLAG, IERROR)
	INTEGER	COMM, COMM_KEYVAL, IERROR 
	INTEGER(KIND=MPI_ADDRESS_KIND) ATTRIBUTE_VAL
	LOGICAL FLAG

USE mpi_f08
MPI_Comm_get_attr(comm, comm_keyval, attribute_val, flag, ierror)
	TYPE(MPI_Comm), INTENT(IN) :: comm
	INTEGER, INTENT(IN) :: comm_keyval
	INTEGER(KIND=MPI_ADDRESS_KIND), INTENT(OUT) :: attribute_val
	LOGICAL, INTENT(OUT) :: flag
	INTEGER, OPTIONAL, INTENT(OUT) :: ierror

#include <mpi.h>
bool MPI::Comm::Get_attr(int comm_keyval, void* attribute_val)
	const

Communicator to which the attribute is attached (handle).
Key value (integer).

Attribute value, unless flag = false.
False if no attribute is associated with the key (logical).
Fortran only: Error status (integer).

MPI_Comm_get_attr retrieves an attribute value by key. The call is erroneous if there is no key with value keyval. On the other hand, the call is correct if the key value exists, but no attribute is attached on comm for that key; in that case, the call returns flag = false. In particular, MPI_KEYVAL_INVALID is an erroneous key value.

This function replaces MPI_Attr_get, the use of which is deprecated. The C binding is identical. The Fortran binding differs in that attribute_val is an address-sized integer.

The MPI standard prescribes portable Fortran syntax for the ATTRIBUTE_VAL argument only for Fortran 90. Sun FORTRAN 77 users may use the non-portable syntax


INTEGER*MPI_ADDRESS_KIND ATTRIBUTE_VAL

where MPI_ADDRESS_KIND is a constant defined in mpif.h and gives the length of the declared integer in bytes.

Almost all MPI routines return an error value; C routines as the value of the function and Fortran routines in the last argument. C++ functions do not return errors. If the default error handler is set to MPI::ERRORS_THROW_EXCEPTIONS, then on error the C++ exception mechanism will be used to throw an MPI::Exception object.

Before the error value is returned, the current MPI error handler is called. By default, this error handler aborts the MPI job, except for I/O function errors. The error handler may be changed with MPI_Comm_set_errhandler; the predefined error handler MPI_ERRORS_RETURN may be used to cause error values to be returned. Note that MPI does not guarantee that an MPI program can continue past an error.

May 26, 2022 4.1.4