9.6. Deprecation warnings while compiling MPI applications
If you see deprecation warnings when compiling MPI applications, it is because your application is symbols / functions that are deprecated in MPI. For example:
shell$ mpicc deprecated-example.c -c
deprecated-example.c: In function 'foo':
deprecated-example.c:6:5: warning: 'MPI_Attr_delete' is deprecated: MPI_Attr_delete was deprecated in MPI-2.0; use MPI_Comm_delete_attr instead [-Wdeprecated-declarations]
MPI_Attr_delete(MPI_COMM_WORLD, 2);
^~~~~~~~~~~~~~~
In file included from deprecated-example.c:2:
/usr/local/openmpi/include/mpi.h:2601:20: note: declared here
OMPI_DECLSPEC int MPI_Attr_delete(MPI_Comm comm, int keyval)
^~~~~~~~~~~~~~~
Note that the deprecation compiler warnings tells you how to upgrade
your code to avoid the deprecation warnings. In this example, it
advises you to use MPI_Comm_delete_attr() instead of
MPI_Attr_delete().
Also, note that even if Open MPI was configured with
--enable-mpi1-compatibility to re-enable removed MPI-1 symbols,
you will still get compiler warnings when you use the removed symbols.
The following is a list of functions that have been deprecated in MPI, and the function that is replacing them. Some functions have been deprecated and removed from the MPI specification, these functions are listed here.
Deprecated symbol (click for more details, below) |
Replaced with (click to go to the corresponding man page) |
MPI version deprecating the symbol |
|---|---|---|
MPI-2.0 (1996) |
||
MPI-2.0 (1996) |
||
MPI-2.0 (1996) |
||
MPI-2.0 (1996) |
||
MPI-2.0 (1996) |
||
MPI-2.0 (1996) |
||
MPI-2.0 (1996) |
||
MPI-2.2 (2009) |
||
MPI-2.2 (2009) |
||
MPI-2.2 (2009) |
||
MPI-4.0 (2021) |
||
MPI-4.0 (2021) |
||
Fortran intrinsics``c_sizeof`` or |
MPI-4.0 (2021) |
9.6.1. MPI_Keyval_create
MPI_Keyval_create has been deprecated and replaced by
MPI_Comm_create_keyval. The C binding of the new function is
identical to the deprecated version. Hence, applications can simply
replace the function that is being invoked.
The Fortran binding differs in that the extra_state argument is an
address-sized integer in the new interfaces (vs. a regular integer in
the old interfaces). Also, the copy and delete callback functions have
Fortran bindings that are consistent with address-sized attributes.
USE mpi
EXTERNAL my_copy_attr_function
EXTERNAL my_copy_delete_function
INTEGER ierror
INTEGER comm_keyval
INTEGER old_extra_state
INTEGER(KIND=MPI_ADDRESS_KIND) new_extra_state
! Old way
CALL MPI_KEYVAL_CREATE(my_copy_attr_function, my_copy_delete_function,
comm_keyval, old_extra_state, ierror)
! New way
CALL MPI_COMM_CREATE_KEYVAL(my_copy_attr_function, my_delete_attr_function,
comm_keyval, new_extra_state, ierror)
9.6.2. MPI_Keyval_free
The binding of MPI_Keyval_free and MPI_Comm_free_keyval are identical
for both C and Fortran. Users can directly replace the deprecated function with its
new version.
9.6.3. MPI_Copy_function and MPI_Delete_function
The MPI_Copy_function and MPI_Delete_function are only used in the
deprecated function MPI_Keyval_create(), as described in the
MPI_COMM_CREATE_KEYVAL.
For C codes, developers can simply use the new, exactly-equivalent
type name (i.e., the return type, number, and type of parameters
didn’t change) MPI_Comm_copy_attr_function, and
MPI_Comm_delete_attr_function respectively.
For Fortran applications, the only difference lies in required integer type for the
extra_state argument, which now has to be an address-sized integer.
9.6.4. MPI_Attr_put
The C binding for the deprecated MPI_Attr_put is identical to its
replacement, MPI_Comm_set_attr. The Fortran binding differ in the
usage of an addressed size integer for the attribute value in the new
MPI_Comm_set_attr vs. a regular integer in MPI_Attr_put.
USE mpi
INTEGER ierror
INTEGER comm_keyval
INTEGER old_attr_val
INTEGER(KIND=MPI_ADDRESS_KIND) new_attr_val
! Old way
CALL MPI_ATTR_PUT(MPI_COMM_WORLD, comm_keyval,
old_attr_val, ierror)
! New way
CALL MPI_COMM_SET_ATTR(MPI_COMM_WORLD, comm_keyval,
new_attr_val, ierror)
9.6.5. MPI_Attr_get
The C bindings of the old and the new interfaces are identical.
Fortran binding differ in the usage of an addressed size integer for
the attribute value in the new MPI_Comm_get_attr vs. a regular
integer in MPI_Attr_get.
9.6.6. MPI_Attr_delete
C and Fortran bindings are identical for MPI_Attr_delete and
MPI_Comm_delete_attr, hence developers should be able to just
directly substitute one function call by the other.
9.6.7. MPI_Info_get
Applications should replace the use of MPI_Info_get with MPI_Info_get_string,
but the usage differs slightly. See the example below.
MPI_Info info;
// Create an info object using MPI_Info_create()
...
// Retrieve the the value of a provided key later in the code
char key[] = "my_key";
char value[64];
int valuelen=64;
int flag;
// Old way
MPI_Info_get(info, key, valuelen, &value, &flag);
// New way
// Note that we pass the address of valuelen with
// the new interfaces, since the variable will
// contain the length of the value string after
// the function call.
MPI_Info_get_string(info, key, &valuelen, &value, &flag);
}
9.6.8. MPI_Info_get_valuelen
MPI_Info_get_valuelen has been deprecated since the new function
MPI_Info_get_string also returns the length of the value string.
Please refer to the example shown in MPI_INFO_GET.
9.6.9. MPI_Sizeof
The MPI_SIZEOF construct in Fortran has been deprected since there
are standard Fortran language constructs such as c_sizeof and
storage_size that can be used instead.
9.6.10. MPI_Comm_errhandler_fn, MPI_File_errhandler_fn, MPI_Win_errhandler_fn
The following function typedefs have been deprecated and are superseded by new names. Other than the typedef names, the function signatures are exactly the same; the names were updated to match conventions of other function typedef names.
MPI_Comm_errhandler_fn→MPI_Comm_errhandler_functionMPI_File_errhandler_fn→MPI_File_errhandler_functionMPI_Win_errhandler_fn→MPI_Win_errhandler_function