Caching on communicators has been a very useful feature. In MPI-// it is expanded to include caching on windows and datatypes.
One difficulty in MPI-/ is the potential for size differences between Fortran integers and C pointers. To overcome this problem with attribute caching on communicators, new functions are also given for this case. The new functions to cache on datatypes and windows also address this issue. For a general discussion of the address size problem, see Section 4.12.6.
The MPI-1.2/ clarification, described in
Section on
page
, about the effect of returning other
than MPI_SUCCESS from attribute callbacks applies to these
new versions as well.