Nathan Hjelm and I stumbled across a question regarding MPI_T today: what guarantees does MPI_T provide about control variable values when MPI_T is finalized and MPI is either not initialized or is finalized? For example: ```C // Block A MPI_T_Init(...); MPI_T_Cvar_read(..., &value_pre); MPI_T_Cvar_write(...); MPI_T_Finalize(...); // ...dead zone where neither MPI_T nor MPI are initialized... // Block B MPI_Init(...) MPI_T_Init(...); MPI_T_Cvar_read(..., &value_post); assert(value_pre == value_post); ``` Is it guaranteed that the assert() in block B must be true? Here's why I ask -- consider the following two scenarios: SCENARIO 1: =========== - Block A causes a dynamically-loaded component to be loaded and initialized - The cvar from that dynamically-loaded component is set to a default value - The cvar is then read into value_pre - The cvar is then assigned a non-default value - MPI_T is then finalized - Since MPI is not initialized, the dynamically-loaded component is unloaded (so that the process can be valgrind clean if it exits) - Block B causes the same dynamically-loaded component to be loaded and initialized - The cvar from that dynamically-loaded component is set to a default value - The cvar is then read into value_post - value_pre and value_post are both the same (default) value -- the assert passes SCENARIO 2: =========== - Block A causes a statically-loaded component to be initialized - The cvar from that statically-loaded component is set to a default value - The cvar is then read into value_pre - The cvar is then assigned a non-default value - MPI_T is then finalized - Since the component is static, it is *not* unloaded - Block B causes nothing to happen to the component (because it's statically loaded) - The cvar from that statically-loaded component ***is still set to the non-default value*** - The cvar is then read into value_post - value_pre and value_post are different values -- the assert fails -- Jeff Squyres [email protected] For corporate legal information go to: http://www.cisco.com/web/about/doing_business/legal/cri/